Dispersing Element, Method for Manufacturing Structure with Conductive Pattern Using the Same, and Structure with Conductive Pattern

ABSTRACT

A conductive pattern having high dispersion stability and a low resistance over a board is formed. A dispersing element ( 1 ) contains a copper oxide ( 2 ), a dispersing agent ( 3 ), and a reductant. Content of the reductant is in a range of a following formula (1). Content of the dispersing agent is in a range of a following formula (2). 
       0.0001≤(reductant mass/copper oxide mass)≤0.10  (1)
 
       0.0050≤(dispersing agent mass/copper oxide mass)≤0.30  (2)
 
     The dispersing element containing the reductant promotes reduction of copper oxide to copper in firing and promotes sintering of the copper.

TECHNICAL FIELD

The present invention relates to a dispersing element, a method formanufacturing a structure with a conductive pattern using the same, andthe structure with the conductive pattern.

BACKGROUND ART

A circuit board has a structure where conductive wiring is wired on aboard. A method for manufacturing the circuit board is typically asfollows. First, a photoresist is applied over a board with a stuck metalfoil. Next, the photoresist is exposed and developed to obtain anegative appearance of a desired circuit pattern. Next, a part of themetal foil not coated with the photoresist is removed by chemicaletching to form a pattern. Thus, high-performance circuit boards can bemanufactured.

However, the conventional method has drawbacks, such as a large numberof steps, complicated processing, and the necessity of a photoresistmaterial.

In contrast to this, a direct wiring printing technique (hereinafterreferred to as printed electronics (PE) method) that directly prints adesired wiring pattern on a board with a dispersing element, produced bydispersing microparticles selected from the group consisting of metalmicroparticles and metal oxide microparticles has been drawingattention. For example, since the number of steps is small and the useof the photoresist material is unnecessary, this technique featuressignificantly high productivity.

The dispersing element includes metal ink and metal paste. The metal inkis a dispersing element produced by dispersing ultrafine metal particleshaving an average particle diameter of several to several tens ofnanometers into a dispersion medium. When the metal ink is applied overthe board and dried, and then a heat treatment is performed on thismetal ink, by lowering of a melting point specific to the ultrafinemetal particles, the metal ink sinters at a temperature lower than amelting point of the metal, thus ensuring forming a metal film having aconductive property (hereinafter also referred to as conductive film).The metal film obtained using the metal ink has a thin film thickness,close to the metal foil.

Meanwhile, the metal paste is a dispersing element produced bydispersing microparticles of metal having a micrometer size into adispersion medium together with binder resin. Since the size of themicroparticles is large, to prevent precipitation, the metal paste isusually supplied in a state of considerably high viscosity. Therefore,the metal paste is suitable for screen-printing and an application witha dispenser appropriate for a material with high viscosity. Since metalparticles of the metal paste have a large size, the metal paste has afeature of ensuring formation of a metal film having a thick filmthickness.

As metal used for such metal particles, copper has been drawingattention. Especially, as a substitution of indium tin oxide (ITO),which has been widely used as an electrode material of a projectedcapacitive touchscreen, copper is the most promising from perspectivesof resistivity, an ion (electrochemical) migration, results as aconductor, a price, a reserve, and the like.

However, the copper in the form of ultrafine particles of several tensof nanometers is likely to oxidize and therefore an antioxidanttreatment is required. The antioxidant treatment had a problem ofhindering sintering.

To solve such problem, there has been proposed the following. Usingultrafine particles of copper oxide as a precursor, the copper oxide isreduced to copper under an appropriate atmosphere by energy, such asheat and active ray to form a copper thin film (for example, see PatentDocument 1).

A surface diffusion itself in the ultrafine particles of the copperoxide occurs at a temperature lower than 300° C. Accordingly, when thecopper oxide is reduced to the copper under the appropriate atmosphereby energy, the superparticles of the copper mutually form fine randomchains through sintering and are entirely shaped like a network, thusensuring obtaining a desired electrical conductivity.

Patent Document 1: WO 2003/051562 A DISCLOSURE OF THE INVENTION Problemsto be Solved by the Invention

As a first problem, the metal thin film obtained by the PE method usingthe metal ink and the metal paste has been requested that a change overtime is small in addition to low resistivity. For example, regarding asilver paste, it has been known that since silver is likely to oxidizeunder the atmosphere and the oxidization increases the resistivity,resistivity between silver particles worsens over time.

However, there are no citations that examined on the stability ofresistivity of the metal film obtained by the PE method using theultrafine particles of the copper oxide disclosed in Patent Document 1as the precursor.

For industrial use, the dispersing element is also requested to haveexcellent dispersion stability against the change over time in highconcentration.

As a second problem, it has been known that, in the conventional PEmethod using the metal paste, which metalizes microparticles of metaloxide by reduction to obtain a metal film, sintering is likely toproceed as the particle diameter becomes small, cracks occur during afiring process, and the resistivity is likely to increase. The sinteringfuses the plurality of microparticles in contact by the interfaces, andthe microparticles mutually take in the others and grow up to be largeparticles. A decrease in surface areas of the particles proceeds then,and clearances present between the plurality of microparticlesdisappear. Consequently, a volume of the application film contracts andthis possibly causes cracks. The crack involves an increase inresistivity of the metal film.

It has been known that when the thickness of the application film of themetal paste becomes larger than 1 μm, cracks are likely to occur in thefiring process and also cracks occur over time and the resistivity ofthe metal film worsens over time.

However, there are no citations that examined on the stability ofresistivity over time, especially cracks generated over time, of themetal film obtained by the PE method using the ultrafine particles ofthe copper oxide disclosed in Patent Document 1 as the precursor.

Further, it has been requested that the dispersing element used for thePE method is also applicable to the screen-printing that can obtain anapplication film having a comparatively thick film, in addition toink-jet printing that can obtain an application film having acomparatively thin film.

Additionally, the metal film is requested to be easily soldered. Forexample, a typical, general-purpose conductive paste is electricallyconducted by physical contact of metal particles (average particlediameter: 0.5 to 2.0 μm) by a hardening shrinkage of a binder resin. Inview of this, the binder resin exudes to the surface of the metal filmand forms a film, making the soldering difficult. The metal film is alsorequested to have high adhesiveness with a solder.

The present invention has been made in consideration of the points, andone object of the present invention is to provide a dispersing elementthat features high dispersion stability and can form a conductivepattern having a low resistance on a board, a method for manufacturing astructure with the conductive pattern using the dispersing element, andthe structure with the conductive pattern.

Additionally, one object is to provide the dispersing element applicableto a screen-printing method and that can obtain the conductive patternexcellent in stability of resistivity over time and a solderingperformance, the method for manufacturing the structure with theconductive pattern using the dispersing element, and the structure withthe conductive pattern.

Solutions to the Problems

As a result of diligent studies to solve the above-described problems,the inventors have completed the present invention. The presentinvention is to solve any one of the first and the second problems.

That is, a dispersing element according to one aspect of the presentinvention contains a copper oxide, a dispersing agent, and a reductant.Content of the reductant is in a range of a following formula (1).Content of the dispersing agent is in a range of a following formula(2).

0.0001≤(reductant mass/copper oxide mass)≤0.10  (1)

0.0050≤(dispersing agent mass/copper oxide mass)≤0.30  (2)

The ranges of the masses of the reductant and the dispersing agent tothat of the copper oxide are limited in this structure. Accordingly,dispersion stability is improved and a resistance of a conductivepattern effectively decreases. Additionally, since a firing process canbe performed using plasma, light, and laser light, an organic matter inthe copper oxide is decomposed, the firing of the copper oxide ispromoted, and the conductive pattern having the low resistance can beformed.

A dispersing element according to one aspect of the present inventioncontains a copper oxide having a particle diameter of 1 nm or more to 50nm or less, copper particles having particle diameters of 0.1 μm or moreto 100 μm or less, and an organic compound having a phosphate group.

With this structure, sintering an application film using the dispersingelement containing the copper particles having the particle diameters ofthe micrometer order and the copper oxide particles of the nanometerorder by the firing process bonds the copper particles together andforms a firm mechanical structure. At the same time, the copper oxideparticles present between the copper particles are reduced by the firingprocess, change into metal copper and sinter, and are integrated withthe copper particles, thus generating an electrical conduction. Amechanical strength and the electrical conduction of the conductivepattern are improved and the stability of resistivity over timeincreases. Additionally, aggregation is less likely to occur andtherefore dispersion stability is excellent and the screen-printingbecomes possible.

A dispersing element according to one aspect of the present inventioncontains a copper oxide and at least one kind of copper particles havingshapes extending in one direction, dendritic shapes, or flat shapes.

With this structure, the copper particles having the shapes of extendingin one direction, the dendritic shapes, or the flat shapes easily align,and many contact points between the particles can be ensured. At thesame time, since the reduced copper oxide particles act as a binder, themechanical strength and the electrical conduction of the conductivepattern are improved and the stability of resistivity over timeincreases. Additionally, the aggregation is less likely to occur andtherefore the dispersion stability is excellent and the screen-printingbecomes possible.

The dispersing element according to one aspect of the present inventionis preferably as follows. The dispersing element contains copperparticles. The copper particles have shapes extending in one direction,dendritic shapes, or flat shapes.

The dispersing element according to one aspect of the present inventionpreferably contains at least the copper particles having the dendriticshapes.

In the dispersing element according to one aspect of the presentinvention, the copper oxide preferably has a particle diameter of 1 nmor more to 50 nm or less.

In the dispersing element according to one aspect of the presentinvention, the copper particles preferably have a mass ratio to a massof the copper oxide of 1.0 or more to 7.0 or less.

In the dispersing element according to one aspect of the presentinvention, the organic compound has a mass ratio to a mass of the copperoxide of 0.0050 or more to 0.30 or less.

The dispersing element according to one aspect of the present inventionis preferably as follows. The dispersing element contains a reductant.The reductant has a mass ratio to a mass of the copper oxide of 0.0001or more to 0.10 or less.

The dispersing element according to one aspect of the present inventionis preferably as follows. The dispersing element contains a reductant.The reductant contains at least one kind selected from the groupconsisting of a hydrazine, a hydrazine hydrate, a sodium, a carbon, apotassium iodide, an oxalic acid, an iron sulfide (II), a sodiumthiosulfate, an ascorbic acid, a tin chloride (II), adiisobutylaluminium hydride, a formic acid, a sodium borohydride, and asulfite.

In the dispersing element according to one aspect of the presentinvention, the copper oxide preferably contains a cuprous oxide.

The dispersing element according to one aspect of the present inventionis preferably as follows. The dispersing element further contains adispersion medium. The dispersion medium is at least one kind selectedfrom the group consisting of a terpineol, a γ-butyrolactone, acyclohexanone, an ethanol, a propylene glycol, a butanol, a propanol, anethylene glycol monoethyl ether acetate, and a tetralin.

The dispersing element according to one aspect of the present inventionis preferably as follows. The dispersing element further contains adispersion medium. Two or more kinds of the dispersion mediums arecontained.

A method for manufacturing a structure with a conductive patternaccording to one aspect of the present invention includes: a step ofapplying the dispersing element over a board to form an applicationfilm; and a step of irradiating the application film with laser light toform a conductive pattern on the board.

A method for manufacturing a structure with a conductive patternaccording to one aspect of the present invention includes: a step ofapplying the dispersing element over a board in a desired pattern toform an application film; and a step of performing a firing process onthe application film to form a conductive pattern on the board.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the firingprocess is preferably performed by generating plasma under an atmospherecontaining a reducing gas.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the firingprocess is preferably performed by a light irradiation method.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the firingprocess is preferably performed by heating the application film withheat at 100° C. or more.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the dispersingelement is preferably applied by an aerosol method to form the desiredpattern.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the dispersingelement is preferably applied by screen-printing.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, after theapplication film is formed on a transfer body, the application film ispreferably transferred from the transfer body to the board to form theapplication film on the board.

The method for manufacturing the structure with the conductive patternaccording to one aspect of the present invention preferably includes: astep of applying the dispersing element over a transfer body and thencontacting a convex portion with the transfer body and removing anunnecessary dispersing element to form a desired pattern on a surface ofthe transfer body; and a step of contacting the board with the surfaceof the transfer body to transfer the desired pattern to the board.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the conductivepattern is preferably an antenna.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, the conductivepattern preferably has a mesh shape.

The method for manufacturing the structure with the conductive patternaccording to one aspect of the present invention preferably furtherincludes a step of forming a solder layer on a part of a surface of theconductive pattern.

In the method for manufacturing the structure with the conductivepattern according to one aspect of the present invention, on theconductive pattern, an electronic component is preferably soldered viathe solder layer by a reflow method.

A structure with a conductive pattern according to one aspect of thepresent invention includes a board, a cuprous-oxide-containing layer,and a conductive layer. The cuprous-oxide-containing layer is formed ona surface of the board. The conductive layer is formed on a surface ofthe cuprous-oxide-containing layer. The conductive layer is a wiringhaving a wire width of 1 μm or more to 1000 μm or less. The wiringcontains a reduced copper.

A structure with a conductive pattern according to one aspect of thepresent invention includes a board, a cuprous-oxide-containing layer,and a conductive layer. The cuprous-oxide-containing layer is formed ona surface of the board. The conductive layer is formed on a surface ofthe cuprous-oxide-containing layer. The conductive layer is a wiringhaving a wire width of 1 μm or more to 1000 μm or less. The wiringcontains a reduced copper, a copper, and a tin.

A structure with a conductive pattern according to one aspect of thepresent invention includes a board and a conductive pattern. Theconductive pattern is formed on a surface of the board. The conductivepattern is a wiring having a wire width of 1 μm or more to 1000 μm orless. The wiring contains a reduced copper, a phosphorus, and a void.

A structure with a conductive pattern according to one aspect of thepresent invention includes a board and a conductive pattern. Theconductive pattern is formed on a surface of the board. The conductivepattern is a wiring having a wire width of 1 μm or more to 1000 μm orless. The wiring contains a reduced copper, a copper, and a tin.

In the structure with the conductive pattern according to one aspect ofthe present invention, the copper preferably has a grain size of 0.1 μmor more to 100 μm or less.

In the structure with the conductive pattern according to one aspect ofthe present invention, the conductive layer or the conductive patternpreferably has a surface having a surface roughness of 500 nm or more to4000 nm or less.

In the structure with the conductive pattern according to one aspect ofthe present invention, the wiring is preferably usable as an antenna.

In the structure with the conductive pattern according to one aspect ofthe present invention, the conductive layer or the conductive patternpreferably has a surface on which a solder layer is partially formed.

A structure with a conductive pattern according to one aspect of thepresent invention includes a board and a conductive pattern. Theconductive pattern is formed on the board surface. The conductivepattern is a wiring having a wire width of 1 μm or more to 1000 μm orless. The wiring contains a reduced copper, a copper oxide, and aphosphorus. A resin is disposed so as to cover the wiring.

Effects of the Invention

According to the present invention, the conductive pattern featuring thehigh dispersion stability and the low resistance on the board can beformed.

Additionally, the conductive pattern applicable to the screen-printingmethod and excellent in stability of resistivity over time and asoldering performance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating states of copper oxide andcopper particles having dendritic shapes before a dispersing elementaccording to a third embodiment is applied over a board and a firingprocess is performed.

FIGS. 2A-2D include cross-sectional schematic diagrams illustrating astructure with a conductive pattern according to an embodiment.

FIG. 3 is an explanatory view illustrating respective steps in the caseof using laser irradiation for firing in a method for manufacturing thestructure with the conductive pattern according to the embodiment.

FIG. 4 is an explanatory view illustrating respective steps in the caseof using plasma for the firing in the method for manufacturing thestructure with the conductive pattern according to the embodiment.

FIG. 5 is a drawing describing a method for forming an application filmusing a transfer body according to the embodiment.

FIGS. 6A-6B include drawings describing another example of the methodfor forming the application film using the transfer body according tothe embodiment.

FIG. 7 is a drawing describing a method for forming a pattern on thetransfer body according to the embodiment.

FIG. 8 is a schematic diagram illustrating a relationship between copperoxide and phosphoric acid ester salt according to the embodiment.

FIGS. 9A-9B are top views of the structure with the conductive patternon which solder layers according to the embodiment are formed.

DESCRIPTION OF PREFERRED EMBODIMENTS

While the following exemplarily describes embodiments of the presentinvention (hereinafter referred to as “embodiments”) in detail, thepresent invention is not limited to the embodiments.

First Embodiment

A dispersing element of the first embodiment contains (1) copper oxide,(2) dispersing agent, and (3) reductant. The dispersing elementcontaining the reductant promotes reduction of copper oxide to copper infiring and promotes sintering of the copper.

The content of the reductant meets a range of the following formula (1).A mass ratio of the reductant of 0.0001 or more improves dispersionstability and decreases a resistance of a copper film. Additionally, themass ratio of 0.1 or less improves long-term stability of the dispersingelement.

0.0001≤(reductant mass/copper oxide mass)≤0.10  (1)

The content of the dispersing agent meets a range of the followingformula (2). This reduces aggregation of the copper oxide and improvesthe dispersion stability.

0.0050≤(dispersing agent mass/copper oxide mass)≤0.30  (2)

The dispersing element of the first embodiment is limited in the rangesof the masses of the reductant and the dispersing agent to that of thecopper oxide. Accordingly, the dispersion stability is improved and aresistance of a conductive film effectively decreases. Additionally,since the firing process can be performed using plasma, light, and laserlight, an organic matter in the copper oxide is decomposed, the firingof the copper oxide is promoted, and the conductive film having the lowresistance can be formed. In view of this, various copper wirings, suchas an electromagnetic wave shield and a circuit, can be provided.

The dispersing element of the first embodiment contains the copperparticles, and the copper particles preferably have shapes extending inone direction, dendritic shapes, or flat shapes. The dispersing elementof the first embodiment more preferably at least contains the copperparticles having the dendritic shapes. Accordingly, for example,compared with particles having spherical shapes or regular polyhedronshapes and having a small aspect ratio, the copper particles having thespecific shapes are likely to get entangled with one another and align.In view of this, many contact points between the particles can beensured, sintering the application film by the firing process forms afirm mechanical structure, and cracks are reduced in the obtainedconductive film.

The dispersing element of the first embodiment contains the copperparticles, and the copper particles preferably have particle diametersof 0.1 μm or more to 100 μm or less, further preferably 0.5 μm or moreto 50 μm or less, and especially preferably 1.0 μm or more to 10 μm orless. Thus, a crack reducing effect is high, and the ultrafine particlesof the nanometer order of the copper oxide enter between the copperparticles and easily work as a binder. This also allows preventing themechanical strengths of the copper particles themselves from decreasing.

The copper oxide in the dispersing element of the first embodimentpreferably has the particle diameter of 1 nm or more to 50 nm or less.Thus, the sintering is facilitated and the copper oxide particles easilyenter between the copper particles and therefore the copper oxideparticles easily act as the binder. Moreover, usage of the dispersingagent can be reduced, making the firing process easy.

Thus, sintering the application film using the dispersing elementcontaining the copper particles having the particle diameters of themicrometer order and the copper oxide particles of the nanometer orderby the firing process bonds the copper particles together and forms thefirm mechanical structure.

Second Embodiment

As a result of diligent examination, the inventors have found thefollowing. The use of the copper oxide particles having specificparticle diameters and the copper particles having specific particlediameters in combination for the dispersing element and the use of thedispersing agent reduce both cracks generated in sintering and cracksgenerated over time, thereby ensuring obtaining a conductive film havinglow resistivity and excellent stability of resistivity over time.

It has been found that although the above-described dispersing elementcontains the ultrafine particles in high concentration, the dispersingelement is less likely to aggregate. Accordingly, it has been found thatthe dispersing element is also applicable to the screen-printing methodand is excellent in printability. Moreover, it has been found that theabove-described dispersing element exhibits excellent dispersionstability against a change over time in high concentration and allowsscreen-printing even after storage over a long period of time.

Furthermore, it has been found that the use of the screen-printingallows forming an application film having a comparatively thick film;therefore, the above-described dispersing element can conduct a largeamount of current by the obtained conductive film.

A soldering performance to the conductive film with the use of theabove-described dispersing element has been found to be satisfactory.

The inventors have completed the present invention based on such newviewpoints. That is, the dispersing element of the second embodimentcontains the copper oxide having the particle diameter of 1 nm or moreto 50 nm or less, the copper particles having the particle diameters of0.1 μm or more to 100 μm or less, and an organic compound having aphosphate group.

Here, the particle diameter is an average particle diameter of primaryparticles of the copper oxide particles and the copper particles.

With the dispersing element according to the second embodiment,sintering the application film using the dispersing element containingthe copper particles having the particle diameters of the micrometerorder and the copper oxide particles of the nanometer order as describedabove by the firing process bonds the copper particles together, thusforming the firm mechanical structure. Since the copper oxide particlesare present between the copper particles, the copper oxide particles arereduced by the firing process, change into the metal copper and sinter,and are integrated with the copper particles, thus generating electricalconduction. In other words, the copper oxide particles act as the binderto the copper particles. Accordingly, the obtained conductive filmreduces cracks caused by sudden strain and residual strain duringsintering. Additionally, the copper particles and the reduced copperoxide particles form a path as a conductor and ensure reducing theresistivity. As a result, the conductive film having the low resistivityand the high stability of resistivity over time can be obtained.

In the dispersing element according to the second embodiment, theparticle diameters of the copper oxide particles have the upper limitvalue of 50 nm. The particle diameter of less than that facilitates thesintering and the copper oxide particles easily enter between the copperparticles and therefore the copper oxide particles are likely to act asthe binder.

With the copper oxide particles having such a size, lowering of amelting point specific to ultrafine metal particles causes the copperoxide particles to sinter at a temperature lower than the melting pointof the metal, thereby ensuring forming the conductive film.

Note that designing the particle diameters of the metal particles tosufficiently decrease increases a proportion of high-energy atoms to allthe atoms in the particle and a surface diffusion of the atoms increasesto a level that cannot be ignored. As a result, caused by the surfacediffusion, interfaces of the mutual particles are stretched, andsintering is performed at a temperature lower than the melting point ofthe metal, which is referred to as the lowering of melting point.

Meanwhile, the particle diameters of the copper oxide particles have thelower limit value of 1 nm. This is because that the particle diameter ofmore than that allows reducing the usage of the dispersing agent andfacilitates the firing process.

The particle diameter is determined from perspectives of denseness andelectrical property of the metal copper obtained by the reductiontreatment of the copper oxide particles. Further, considering the use ofa resin board, the firing condition needs to further lower thetemperature from a perspective of reducing damage given to the board andtherefore a further small particle diameter is preferred. With theprimary particle diameter of 50 nm or less, there is a tendency thatinput energy can decrease such that the board is not damaged further bythe condition in the firing process described later.

In the dispersing element according to the second embodiment, theparticle diameters of the copper particles have the upper limit value of100 μm. This is because that the upper limit value less than that bringsthe high crack reducing effect and the ultrafine particles of thenanometer order of the copper oxide enter between the copper particlesand easily work as the binder.

Meanwhile, the average particle diameter of the copper particles has thelower limit value of 0.1 μm. This allows preventing a decrease inmechanical strength of the copper particles themselves.

The dispersing element according to the second embodiment contains thecomparatively large copper particles and contains the dispersing agent.As long as the copper oxide particles are dispersible, the dispersingagent is usable without restrictions; however, the dispersing agent ispreferably the organic compound having the phosphate group. In view ofthis, although containing the comparatively small copper oxideparticles, the dispersing agent is less likely to aggregate andpreferably usable for the screen-printing method. This allows preventingthe aggregated particles from getting stuck in a supply passage from anaccumulation container for ink to a screen in a printing device used forthe screen-printing method, a screen mesh, or the like. Since thedispersing element according to the second embodiment exhibits theexcellent dispersion stability against the change over time in highconcentration, the screen-printing can be performed even after storageover a long period of time.

The screen-printing can form an application film as a line patternhaving a comparatively wide width, for example, 100 μm and having acomparatively thick film thickness and therefore is appropriate forformation of a conductive film that can flow large electricity.Currently, the dispersing element according to the second embodiment ispreferably usable for an application using expensive silver ink.Although a screen-printing device using silver ink has been popular,since the existing screen-printing device is usable, the silver ink canbe easily substituted by copper ink.

When the dispersing element according to the second embodiment isapplied over the board by screen-printing, the comparatively largecopper particles are contained; therefore, the application film becomesbulky, and as a result, the application film having a comparativelythick film thickness can be formed.

When the application film can be formed with the dispersing elementusing the copper by screen-printing, the thick application film can beformed as described above, and as a result, this leads to ensure theformation of the conductive film having the thick film (for example, 1μm or more to 100 μm or less). The conductive board including theconductive film having such a film thickness has a high conductiveproperty and therefore is appropriate for an application, such as atransparent conductive film and an electromagnetic wave shield. With thedispersing element according to the second embodiment, silver can beexchanged for copper and a cost of these products can be substantiallyreduced.

In the second embodiment, the printing refers to a configuration of adesired pattern (typically including a character, an image, a design,and the like) on a medium with ink (one aspect of the dispersing elementof the present invention) and is a concept included in an application.

With the dispersing element according to the second embodiment, thefiring operation decomposes an organic component, such as a dispersionmedium, which deteriorates a soldering performance. Accordingly,wettability of a solder to the conductive film obtained by the use ofthe dispersing element is enhanced, making the soldering easy.

With the dispersing element of the second embodiment, the copperparticles preferably have the shapes extending in one direction, thedendritic shapes, or the flat shapes. The dispersing element of thesecond embodiment more preferably at least contains the copper particleshaving the dendritic shapes. Accordingly, for example, compared withparticles having spherical shapes or regular polyhedron shapes andhaving a small aspect ratio, the copper particles having the specificshapes are likely to get entangled with one another and align. In viewof this, the many contact points between the particles can be ensured,sintering the application film by the firing process forms the firmmechanical structure, and cracks are reduced in the obtained conductivefilm.

With the dispersing element according to the second embodiment, theorganic compound preferably has a mass ratio to the mass of the copperoxide particles of 0.0050 or more to 0.30 or less. The organic compoundhaving the phosphate group as the dispersing agent in this range reducesthe aggregation of the copper oxide and improves the dispersionstability.

Third Embodiment

As a result of diligent examination, the inventors have found thefollowing. The use of the dispersing element containing the copper oxideparticles and the copper particles having a specific grain shape canobtain a conductive film that reduces both cracks generated duringsintering and cracks generated over time, and has low resistivity andexcellent stability of resistivity over time.

It has been found that although the above-described dispersing elementcontains the ultrafine particles in high concentration, the dispersingelement is less likely to aggregate. Accordingly, it has been found thatthe dispersing element is also applicable to the screen-printing methodand is excellent in printability. Moreover, it has been found that theabove-described dispersing element exhibits excellent dispersionstability against a change over time in high concentration and allowsscreen-printing even after storage over a long period of time.

Furthermore, it has been found that the use of the screen-printingallows forming an application film having a comparatively thick film;therefore, the above-described dispersing element can conduct a largeamount of current by the obtained conductive film.

A soldering performance to the conductive film with the use of theabove-described dispersing element has been found to be satisfactory.

The inventors have completed the present invention based on such newviewpoints. That is, the dispersing element according to the thirdembodiment contains the copper oxide and at least one kind of the copperparticles having the shapes extending in one direction, the dendriticshapes, or the flat shapes (hereinafter also referred to as the copperparticles having the specific shapes).

The particles having the shapes extending in one direction can bedescribed as follows. First, here, the shape is the shape of the primaryparticle. Next, an extension direction of the particle is defined as alongitudinal direction and the maximum value of the longitudinaldirection is defined as a length (L). A direction perpendicular to thelongitudinal direction is defined as a width direction and the maximumvalue of the width direction is defined as a width (W). A ratio of thelength (L) to the width (W) of the particle is defined as the aspectratio. It can be said that the shape where the aspect ratio exceeds 1 isthe shape extending in one direction.

Specifically, the shape extending in one direction includes a needleshape, a pillar shape, a thread shape, a string shape, a wire shape, arod shape, a spindle shape, and the like. Here, a difference between theneedle shape and the pillar shape is not a difference in shape but thesize of the particle. That is, even having the similar shapes, the shapehaving the comparatively long width (W) is referred to as the pillarshape and the shape having the short width (W) is referred to as theneedle shape.

The shape extending in one direction is not limited to a case where asize of a cross-sectional surface is constant along the extensiondirection of the particle and a part larger than or smaller than theother part may be present. When the particle is regarded as a columnhaving an equal volume, the width (W) in this case is a diameter of abottom surface of this column.

Although the shape of the cross-sectional surface of the particle is notspecifically limited, a shape may be a circle, a triangular shape, aquadrangular shape, a polygon other than those shapes, and a shapeconnected with a curved line and a straight line.

The particle is not limited to have a shape linearly extending in theextension direction and may be a shape extending curvedly. In this case,the shape of the particle is referred to as a hairy shape, the threadshape, the string shape, the wire shape, and a similar shape.

The shapes of the particles extending in one direction facilitatealigning the particles and the many contact points between the particlescan be ensured. From this perspective, the aspect ratio of the particleis preferably 3 or more.

In the third embodiment, the dendritic shape can be described asfollows. First, here, the shape is the shape of the primary particle.Next, the dendritic shape is constituted of a main having theabove-described shape extending in one direction and at least one branchbranched from the main. This shape is also referred to as a dendriteshape.

The dendritic shapes of the particles facilitate aligning the particlesand the many contact points between the particles can be ensured. Thedendritic shapes allow the particles to get entangled with one anotherthree-dimensionally. From these perspectives, the aspect ratio of themain of this particle is preferably 3 or more. Although the number ofbranches is not specifically limited, two or more is preferred and threeor more is especially preferred. Note that the aspect ratio of the mainis identical to the aspect ratio described about the above-describedparticle having the shape extending in one direction.

In the third embodiment, the flat shape can be described as follows.First, here, the shape is the shape of the primary particle. Next, theflat shape is a shape having a principal surface forming a planarsurface or a curved surface. The maximum length (a) of this principalsurface is defined in the longitudinal direction and the maximum length(b) perpendicular to the longitudinal direction (a) is defined in thelateral direction. A ratio of the length (a) in the longitudinaldirection of the principal surface to a thickness (c) of this particleis defined as the aspect ratio. The shape where the aspect ratio exceeds3 can be said to be the flat shape.

Specifically, the flat shape includes a plate shape, a leaf-like shape,a scaly shape (also referred to as flake shape), and the like. Here, adifference between the plate shape, the leaf-like shape, and the scalyshape is not a difference in shape but the size of the particle. Thatis, even having the similar shapes, the shape having the comparativelythick thickness (c) is referred to as the plate shape, a thinner shapeis referred to as the leaf-like shape, and further thinner shape isreferred to as the scaly shape.

The flat shapes of the particles facilitate aligning the particles andthe many contact points between the particles can be ensured. From theseperspectives, the aspect ratio of this particle is preferably 5 or more.

The dispersing element according to the third embodiment more preferablycontains at least the copper particles having the dendritic shapes.

With the dispersing element according to the third embodiment, forexample, compared with particles having spherical shapes or regularpolyhedron shapes and having a small aspect ratio, the copper particleshaving the specific shapes are likely to get entangled with one anotherand align. In view of this, the many contact points between theparticles can be ensured.

In view of this, sintering the application film by the firing processforms the firm mechanical structure. Since the copper oxide particlesare present between the copper particles, the copper oxide particles arereduced by the firing process, change into the metal copper and sinter,and are integrated with the copper particles, thus generating theelectrical conduction. In other words, the copper oxide particles act asthe binder to the copper particles. Accordingly, the obtained conductivefilm reduces cracks caused by the sudden strain and the residual strainduring sintering. Additionally, the copper particles and the reducedcopper oxide particles form a path as a conductor and ensure reducingthe resistivity. As a result, the conductive film having the lowresistivity and the high stability of resistivity over time can beobtained.

The dispersing element according to the third embodiment contains thecopper particles having the specific shapes. In view of this, thedispersing agent is less likely to aggregate and preferably usable forthe screen-printing method. This allows preventing the aggregatedparticles from getting stuck in the supply passage from the accumulationcontainer for ink to the screen in the printing device used for thescreen-printing method, the screen mesh, or the like.

Currently, the dispersing element according to the third embodiment ispreferably usable for the application using the expensive silver ink.Although the screen-printing device using silver ink has been popular,since the existing screen-printing device is usable, the silver ink canbe easily substituted by the copper ink.

When the dispersing element according to the third embodiment is appliedover the board by screen-printing, the copper particles having thespecific shapes are contained; therefore, the application film becomesbulky, and as a result, the application film having a comparativelythick film thickness can be formed.

The conductive board including the conductive film having such a filmthickness has the high conductive property and therefore is appropriatefor an application, such as the transparent conductive film and theelectromagnetic wave shield. With the dispersing element according tothe third embodiment, silver can be exchanged for copper and a cost ofthese products can be substantially reduced.

Since the dispersing element according to the third embodiment containsthe copper particles having the specific shapes, the dispersing elementis less likely to aggregate, and exhibits excellent dispersion stabilityagainst the change over time in high concentration. In view of this, thescreen-printing can be performed even after storage over a long periodof time.

With the dispersing element according to the third embodiment, thefiring operation decomposes the organic component, such as thedispersion medium, which deteriorates the soldering performance.Accordingly, the wettability of the solder to the conductive filmobtained by the use of the dispersing element is enhanced, making thesoldering easy.

Especially, the dispersing element according to the third embodimentcontaining the copper particles having the dendritic shapes enhances theabove-described effects and therefore is optimal.

FIG. 1 is a schematic diagram illustrating states of the copper oxideand the copper particles having the dendritic shapes before thedispersing element according to the third embodiment is applied over theboard and the firing process is performed. As illustrated in FIG. 1, inan application film 1 before firing, a plurality of copper particles 5having the dendritic shapes get entangled with one another or align. Inview of this, the copper particles 5 are in contact at a plurality ofcontact points X. Copper oxide particles 2 having small particlediameters enter between these copper particles 5.

Since the copper particles 5 having the dendritic shapes are in contactwith one another at branches 5 b branched from mains 5 a, the number ofcontact points X is larger than that of the copper particles having theshapes extending in one direction without branches. Consequently, thecopper particles 5 are further likely to disperse and less likely toaggregate in the dispersing element and the application film 1.Consequently, the above-described effects are provided more remarkably.

With the dispersing element of the third embodiment, the copperparticles preferably have the particle diameters of 0.1 μm or more to100 μm or less, further preferably 0.5 μm or more to 50 μm or less, andespecially preferably 1.0 μm or more to 10 μm or less. Thus, the crackreducing effect is high, and the ultrafine particles of the nanometerorder of the copper oxide enter between the copper particles and easilywork as the binder. This also allows preventing the mechanical strengthsof the copper particles themselves from decreasing.

The copper oxide in the dispersing element of the third embodimentpreferably has the particle diameter of 1 nm or more to 50 nm or less.Thus, the sintering is facilitated and the copper oxide particles easilyenter between the copper particles and therefore the copper oxideparticles easily act as the binder. Moreover, the usage of thedispersing agent can be reduced, making the firing process easy.

Thus, sintering the application film using the dispersing elementcontaining the copper particles having the particle diameters of themicrometer order and the copper oxide particles of the nanometer orderby the firing process bonds the copper particles together and forms thefirm mechanical structure.

<Other Aspects>

With the dispersing elements of the second and the third embodiments,the mass ratio of the copper particles to the mass of the copper oxideparticles is preferably 0.5 or more to 10 or less. The mass ratio of thecopper particles to the mass of the copper oxide particles is morepreferably 1.0 or more to 7.0 or less. The mass ratio of the copperparticles to the mass of the copper oxide particle is further preferably1.5 or more to 6.0 or less. With the copper particle mass ratio withinthis range, the copper oxide is abundantly present; therefore, bondingof the copper particles obtained through the reduction becomessufficient. In view of this, the mechanical strength of the conductivefilm after the firing becomes high. The crack reducing effect brought bythe copper particles obtained through the reduction is sufficientlyprovided.

The dispersing elements according to the second and the thirdembodiments contain the reductant and the mass ratio of the reductant tothe mass of the copper oxide is preferably 0.0001 or more to 0.10 orless. Defining the mass ratio of the reductant improves the dispersionstability and decreases the resistance of the copper film and alsoimproves the long-term stability of the dispersing element.Additionally, the crack reducing effect is high, and the ultrafineparticles of the nanometer order of the copper oxide enter between thecopper particles and easily work as the binder. This also allowspreventing the mechanical strengths of the copper particles themselvesfrom decreasing. The comparatively large copper particles are containedand the organic compound having the phosphate group is contained as thedispersing agent. Accordingly, although the comparatively small copperoxide particles are contained, the aggregation is less likely to occur.

Additionally, in the first to the third embodiments, the reductant iscontained. The reductant preferably contains at least one kind selectedfrom the group consisting of a hydrazine, a hydrazine hydrate, a sodium,a carbon, a potassium iodide, an oxalic acid, an iron sulfide (II), asodium thiosulfate, an ascorbic acid, a tin chloride (II), adiisobutylaluminium hydride, a formic acid, a sodium borohydride, and asulfite. This improves the dispersion stability of the copper oxide anddecreases the resistance of the conductive film.

Additionally, the reductant is especially preferred to be hydrazine orhydrazine hydrate. The use of the hydrazine or the hydrazine hydrate asthe reductant of the dispersing element further improves the dispersionstability of the copper oxide, contributes to the reduction of thecopper oxide in firing, and further decreases the resistance of theconductive film. In reverse printing, a drying rate of the dispersingelement can be regulated. Furthermore, a copper wire having a highdefinition (for example, 0.1 to 5 μm) wire width can be formed, andespecially, the copper wire having the wire width of 5 μm or less isinvisible by the eyes of a human and therefore is preferred as atransparent conductive film.

Additionally, in the first to the third embodiments, the copper oxide ispreferably the cuprous oxide. This facilitates the reduction of thecopper oxide and allows easily sintering the copper generated throughthe reduction.

In the first to the third embodiments, the dispersion medium is furthercontained. The dispersion medium is preferably at least one kindselected from the group consisting of terpineol, γ-butyrolactone,cyclohexanone, ethanol, propylene glycol, butanol, propanol, ethyleneglycol monoethyl ether acetate, and tetralin. While these dispersionmediums may have a reduction action, when the dispersing elementcontains the above-described reductant, the reductant serves as thedispersion medium.

In the first to the third embodiments, the dispersion medium is furthercontained. Two or more kinds of the dispersion mediums are preferablycontained.

<Structure with Conductive Pattern>

The structure with the conductive pattern includes the board and theconductive pattern formed on the surface of the board. The conductivepattern is the wiring having the wire width of 1 μm or more to 1000 μmor less and contains reduced copper, phosphorus, and a void. Thisconfiguration allows forming the wiring having the satisfactory shape onthe board having a desired shape as described later.

The structure with the conductive pattern includes the board and theconductive pattern formed on the surface of the board. The conductivepattern is the wiring having the wire width from 1 μm or more to 1000 μmor less. The wiring contains reduced copper, copper, and tin.

The structure with the conductive pattern includes the board, acuprous-oxide-containing layer, and the conductive layer. Thecuprous-oxide-containing layer is formed on the surface of the board.The conductive layer is formed on a surface of thecuprous-oxide-containing layer. The conductive layer is the wiringhaving the wire width of 1 μm or more to 1000 μm or less. The wiringcontains reduced copper.

The structure with the conductive pattern includes the board, thecuprous-oxide-containing layer, and the conductive layer. Thecuprous-oxide-containing layer is formed on the surface of the board.The conductive layer is formed on the surface of thecuprous-oxide-containing layer. The conductive layer is the wiringhaving the wire width of 1 μm or more to 1000 μm or less. The wiringcontains reduced copper, copper, and tin. The cuprous-oxide-containinglayer is a layer having a ratio of copper to oxygen, Cu/O, of 0.5 ormore to 3.0 or less. An analysis of a cross-sectional surface of thestructure with the conductive pattern by EDX method allows quantitatingCu/O in the cuprous-oxide-containing layer.

In the structure with the conductive pattern, the wiring is preferablyusable as an antenna. This configuration allows forming the antennahaving a satisfactory shape.

In the structure with the conductive pattern, the conductive layer orthe conductive pattern preferably has the surface on which the solderlayer is partially formed. Since the conductive pattern is formed byfiring the copper oxide in the dispersing element, an organic binder isdecomposed in the firing process. In view of this, the wettability ofthe solder becomes high in the conductive pattern and the solder layercan be easily formed. This facilitates soldering electronic componentsin the conductive pattern compared with a conductive pattern formedwithout using the above-described dispersing element.

The structure with the conductive pattern includes the board and theconductive pattern. The conductive pattern is formed on the surface ofthe board. The conductive pattern is the wiring having the wire width of1 μm or more to 1000 μm or less. The wiring contains reduced copper,copper oxide, and phosphorus. Resin is disposed so as to cover thewiring.

(Configuration of Structure with Conductive Pattern)

The use of the dispersing elements according to the first to the thirdembodiments allows obtaining two kinds of the structures with theconductive patterns by methods of firing. FIGS. 2A-2D includescross-sectional schematic diagrams illustrating the structure with theconductive pattern according to the embodiment. Forming the applicationfilm with the dispersing element on the board and irradiating the copperoxide particles of the dispersing element with laser and firing thecopper oxide particles allow obtaining the structure with the conductivepattern of FIG. 2A. A desired pattern is printed with the dispersingelement on the board and firing this pattern with plasma allow obtainingthe structure with the conductive pattern of FIG. 2B.

As illustrated in FIG. 2A, a structure with a conductive pattern 10 mayinclude a board 11 and a superficial layer 14 that includes insulatingregions 12 containing copper oxide and a phosphorus-containing organicmatter and conductive pattern regions 13 containing reduced copperproduced by reduction of copper oxide by firing disposed adjacent to oneanother in a cross-sectional surface view on the surface constituted bythe board 11. The conductive pattern region 13 contains a phosphoruselement derived from the phosphorus-containing organic matter as thedispersing agent. The conductive pattern region 13 is formed by firingcopper oxide ink as the dispersing element; therefore, the organicbinder contained in the dispersing element is decomposed in the firingprocess, and the wettability of the solder becomes high in the obtainedconductive pattern region 13. Accordingly, compared with the conductivepattern formed without the use of the dispersing element, the solderlayer described later can be easily formed on the surface of theconductive pattern region 13 and the electronic component is easilysoldered.

As illustrated in FIG. 2B, the structure with the conductive pattern 10may include the board 11 and the conductive pattern regions 13containing reduced copper in the cross-sectional surface view on thesurface constituted by the board 11. The conductive pattern region 13contains a phosphorus element. In the conductive pattern region 13,since the organic binder contained in the dispersing element iseffectively decomposed in the step of firing the dispersing element, thewettability of the solder becomes effectively high in the conductivepattern region 13. Accordingly, the solder layer can be further easilyformed on the surface of the conductive pattern region 13.

The conductive pattern region 13 may contain, for example, a part ofcuprous oxide as copper oxide particles not reduced in the firingprocess. The conductive pattern region 13 may contain the copperproduced by firing the copper particles of the dispersing element of thesecond and the third embodiments or may contain tin. The insulatingregion 12 and the conductive pattern region 13 may contain a void. Thepresence of the void (hollow wall) in the conductive pattern region 13causes the solder to enter into the void and improves adhesivenessbetween the conductive pattern region 13 and the solder layer.Incidentally, the solder refers to metal containing tin.

Further, the superficial layer 14 does not mean one entirely homogeneousbut, like a relationship between the insulating region 12 and theconductive pattern region 13, may differ in electrical conductivity, aparticle state (fired and not fired), or the like, or a boundary(interface) may be present between both.

In this case, for example, as illustrated in FIG. 2C, on a conductivelayer 18, for example, a cuprous-oxide-containing layer 17 containingcuprous oxide as copper oxide particles not reduced in the firingprocess may be formed on the surface of the board 11. The conductivelayer 18 containing reduced copper formed by reduction of the copperoxide particles may be formed on the surface of thecuprous-oxide-containing layer 17. Thus, the formation of thecuprous-oxide-containing layer 17 improves adhesiveness between theboard 11 and the conductive layer 18 and therefore is preferred. From aperspective of the adhesiveness between the board 11 and the conductivelayer 18, the layer thickness of the cuprous-oxide-containing layer 17is preferably 0.005 μm or more to 8 μm or less, more preferably 0.05 μmor more to 5 μm or less, further preferably 0.1 μm or more to 3 μm orless, and especially preferably 0.2 μm or more to 1 μm or less.

As illustrated in FIG. 2D, the conductive layer 18 may contain copper(Cup) produced by firing the copper particles in the dispersing elementof the second and the third embodiments together with reduced copper(Cu) produced by reducing the copper oxide particles. The conductivelayer 18 may include a void. The presence of the void in the conductivelayer 18 causes tin (Sn) contained in the solder to enter into the void.This improves the adhesiveness between the conductive layer 18 and thesolder layer. Furthermore, the presence of the reduced copper (Cu)around the copper (Cup) further increases the adhesiveness between theconductive layer 18 and the tin (Sn). The particle diameter of thereduced copper (Cu) at this time is preferably 5 to 20 nm.

The coppers contained in the conductive pattern region 13 and theconductive layer 18 preferably have grain sizes of 0.1 μm or more to 100μm or less, 0.5 μm or more to 50 μm or less is further preferred, and1.0 μm or more to 10 μm or less is especially preferred. Here, the grainsize means the size of the metal after firing. This increases theadhesiveness between conductive pattern region 13 and the conductivelayer 18, and the solder layer.

The surface roughnesses of the surfaces of the conductive pattern region13 and the conductive layer 18 are preferably 500 nm or more to 4000 nmor less, more preferably 750 nm or more to 3000 nm or less, and furtherpreferably 1000 nm or more to 2000 nm or less. This facilitates adhesionof the solder layer to the conductive pattern region 13 and theconductive layer 18 and increases the adhesiveness between theconductive pattern region 13 and the conductive layer 18, and the solderlayer.

As illustrated in FIGS. 2A-2D, the formation of the conductive patternregions 13 or the conductive layer 18 allows drawing the wiring havingthe wire width of 0.1 μm or more to 1 cm or less, and the wiring isusable as a copper wiring or an antenna. Exercising the feature of thenano particles of the copper oxide particles contained in the dispersingelement, the wire width of the conductive pattern region 13 or theconductive layer 18 is more preferably 0.5 μm or more to 10000 μm orless, further preferably 1 μm or more to 1000 μm or less, further morepreferably 1 μm or more to 500 μm or less, yet further more preferably 1μm or more to 100 μm or less, and especially preferably 1 μm or more to5 μm or less. The wire width of 5 μm or less cannot visually perceivethe conductive pattern region 13 or the conductive layer 18 as thewiring and therefore is preferred from the perspective of designability.

The conductive pattern may be formed into a mesh shape. The mesh shaperefers to wiring in a grid shape that increases transmittancy andbecomes transparent and therefore is preferred.

The board used in the embodiment has a surface forming the applicationfilm and may have a plate shape or may be a three-dimensional object. Inthe embodiment, a conductive pattern can be formed on a surfaceincluding a curved surface, a step, and the like constituted by thethree-dimensional object. The board in the embodiment means a boardmaterial of a circuit board sheet to form a wiring pattern, a casingmaterial of a casing with wiring, or the like.

A light-transmitting resin layer (not illustrated) may be disposed so asto cover the superficial layer 14 or the conductive pattern region 13.In the method for manufacturing the structure with the conductivepattern 10 described later, the resin layer prevents the applicationfilm from touching oxygen during light irradiation and allows promotingthe reduction of the copper oxide. This sets a peripheral area of theapplication film in an oxygen-free atmosphere or a low-oxygen atmosphereduring light irradiation. For example, this eliminates the need forfacility for a vacuum atmosphere or an inert gas atmosphere, therebyensuring saving a manufacturing cost. Additionally, the resin layer canprevent the conductive pattern region 13 from peeling or scattering dueto heat by light irradiation or the like. This allows manufacturing thestructures with the conductive patterns 10 at a good yield.

<Method for Manufacturing Structure with Conductive Pattern>

The method for manufacturing the structure with the conductive patternincludes a step of applying the dispersing element over the board toform the application film and a step of irradiating the application filmwith laser light to form the conductive pattern on the board. Performingthe firing by laser irradiation allows performing the firing of thecopper particles of the dispersing element and the formation of theconductive pattern at once.

The method for manufacturing the structure with the conductive patternincludes a step of applying the dispersing element on the board in adesired pattern to form the application film and a step of performingthe firing process on the application film to form the conductivepattern on the board.

At this time, the firing process is preferably performed by generatingplasma under an atmosphere containing reducing gas. The firing processis preferably performed by light irradiation method. Additionally, thefiring process is preferably performed by heating the application filmby heat at 100° C. or more.

[Method for forming Conductive Film (Conductive Pattern)]

The method for forming the conductive film of the embodiment reduces thecopper oxide in the application film to generate the copper, and fusesitself and fuses with the copper particles added to the copper oxide inkas the dispersing element to be integrated to form the conductive film(copper film). This step is referred to as firing. Therefore, as long asthe method can form the conductive film through the reduction and thefusion of the copper oxide and the integration with the copperparticles, the method is not especially restricted. The firing in themethod for forming the conductive film of the embodiment, for example,may be performed with a kiln, or may be performed by the use of plasma,infrared, a flash lamp, laser, and the like alone or in combination ofthese methods. After the firing, the solder layer described later can beformed on a part of the conductive film.

With reference to FIG. 3, the following further specifically describesthe method for manufacturing the structure with the conductive patternusing the laser irradiation for the firing according to the embodiment.FIG. 3 is an explanatory view illustrating respective steps in the caseof using the laser irradiation for the firing in the method formanufacturing the structure with the conductive pattern according to theembodiment. In (a) of FIG. 3, copper acetate is dissolved in mixedsolvent of water and propylene glycol (PG), and hydrazine is added andstirred.

Next, in (b) and (c) of FIG. 3, the product is separated intosupernatant and precipitate by centrifugation. Next, in (d) of FIG. 3,dispersing agent and alcohol are added to the obtained precipitate andthen the product is dispersed.

Next, in (e) and (f) of FIG. 3, concentration and dilution are repeatedwith a UF membrane module and the solvent is substituted to obtain adispersing element I (copper oxide ink) containing copper oxide.

In (g) and (h) of FIG. 3, the dispersing element I is applied over aboard made of, for example, PET (described as “PET” in (h) of FIG. 3) byspray coating method to form an application layer (application film)(described as “Cu₂O” in (h) of FIG. 3) containing copper oxide and aphosphorus-containing organic matter.

Next, in (i) of FIG. 3, the application layer is, for example,irradiated with laser to selectively fire a part of the applicationlayer and the copper oxide is reduced to copper (described as “Cu” in(i) of FIG. 3). As a result, in (j) of FIG. 3, the structure with theconductive pattern including the superficial layer in which insulatingregions (described as “A” in (j) of FIG. 3) containing copper oxide anda phosphorus-containing organic matter and conductive film (conductivepattern) regions (described as “B” in (j) of FIG. 3) containing copperand a phosphorus element are disposed adjacent to one another isobtained on the board. The conductive pattern region is usable as awiring.

The conductive pattern region may contain, for example, cuprous oxide ascopper oxide particles not reduced in the firing process. The insulatingregion and the conductive pattern region may contain the copper producedby firing the copper particles of the dispersing element of the secondand the third embodiments or may contain tin. The insulating region andthe conductive pattern region may contain a void. The presence of thevoid in the conductive pattern region causes the solder to enter intothe void and improves adhesiveness between the conductive pattern regionand the solder layer.

Further, the superficial layer does not mean one entirely homogeneousbut, like a relationship between the insulating region and theconductive pattern region, may differ in electrical conductivity, aparticle state (fired and not fired), or the like, or a boundary(interface) may be present between both. The formation of the layer ofthe copper oxide not reduced between the board and the superficial layerimproves the adhesiveness between the board and the superficial layerand therefore is preferable.

Thus, performing the firing by laser irradiation allows performing thefiring of the copper particles of the dispersing element and theformation of the conductive pattern at once. Moreover, since firing thecopper particles decomposes the organic binder contained in thedispersing element, the wettability of the solder increases in theobtained conductive pattern.

Next, with reference to FIG. 4, the following further specificallydescribes the method for manufacturing the structure with the conductivepattern using plasma for the firing according to the embodiment. FIG. 4is an explanatory view illustrating respective steps in the case ofusing plasma for the firing in the method for manufacturing thestructure with the conductive pattern according to the embodiment. Thesteps of (a) to (f) of FIG. 4 are similar to those of FIG. 3.

In (g) and (k) of FIG. 4, on the board made of, for example, PET, thedispersing element I is printed in a desired pattern by, for example,ink-jet printing to form an application layer containing copper oxideand a phosphorus-containing organic matter (described as “Cu₂O” in (k)of FIG. 4).

Next, in (k) of FIG. 4, the application layer is, for example,irradiated with plasma and fired to reduce the copper oxide into copper.As a result, in (l) of FIG. 4, a conductive board in which conductivepattern regions (described as “B” in (l) of FIG. 4) containing thecopper and a phosphorus element are formed is obtained on the board.

Thus, the firing by the plasma irradiation allows firing the copperparticles of the dispersing element printed in the desired pattern byink-jet printing or the like. Additionally, since the organic bindercontained in the dispersing element is effectively decomposed, thewettability of the solder becomes effectively high in the obtainedconductive pattern region.

(Method for Forming Application Film on Board with Dispersing Element)

In the method for manufacturing the structure with the conductivepattern, the desired pattern is preferably formed by application of thedispersing element by aerosol method, and the dispersing element ispreferably applied by screen-printing. The dispersing elements accordingto the first to the third configurations have viscosity and flowcharacteristics appropriate for screen-printing and are therefore arepreferably usable for screen-printing.

The method for manufacturing the structure with the conductive patternforms the application film on a transfer body and then preferablytransfers the application film from the transfer body to the board toform the application film on the board.

FIG. 5 is a drawing describing the method for forming the applicationfilm using the transfer body according to the embodiment. FIGS. 6A-6Bare drawings describing another example of the method for forming theapplication film using the transfer body according to the embodiment.

As illustrated in FIG. 5, a dispersing element 31 is transferred to atransfer body 30 in a desired pattern. On the surface of the transferbody 30 where the dispersing element 31 has been transferred, forexample, a column-shaped board 40 (a circular shape in thecross-sectional surface view) is placed, and then a pressing plate 50 isput on the board 40. While the board 40 is pressed to the transfer body30 with the pressing plate 50, the board 40 is rotated on the transferbody 30. This transfers the dispersing element 31 on the transfer body30 to the board 40.

Thus, when the board 40 is pressed to the surface of the transfer body30 on which the dispersing element 31 has been transferred, the transferbody 30 and the board 40 are in line contact. In view of this, inaddition to the case of the printing surface of the board 40 being aplane, fine printing is possible also in the case of the printingsurface being a curved surface and having ups and downs.

As illustrated in FIG. 6A, the dispersing element 31 is transferred tothe transfer body 30 in a desired pattern. Then, by moving the transferbody 30 relative to the board 40 in the printing direction whilepressing the transfer body 30 against the board 40, the dispersingelement 31 on the transfer body 30 may be transferred to the board 40 asillustrated in FIG. 6B. The transfer body 30 may have the plate shape asillustrated in FIG. 5 or may have the curved surface as illustrated inFIGS. 6A-6B. Thus, the dispersing element 31 is transferred from thetransfer body 30 to the board 40 by a predetermined pressing force, evenwhen the printing surface of the board 40 is curved, satisfactoryprinting is possible.

The formation of the desired pattern in the method for manufacturing thestructure with the conductive pattern preferably includes a step ofapplying the dispersing element over the transfer body and thencontacting a convex portion to the transfer body and removing anunnecessary dispersing element to form a desired pattern on the surfaceof the transfer body, and a step of contacting the board with thesurface of the transfer body to transfer the desired pattern to theboard.

The following describes the method for forming the desired pattern tothe transfer body with reference to FIG. 7. FIG. 7 is a drawingdescribing the method for forming the pattern to the transfer bodyaccording to the embodiment.

As illustrated in FIG. 7, for example, convex portions 60 of a mold arebrought into contact with the dispersing element 31 applied over thesurface of the transfer body 30 to remove the dispersing elements atparts contacted by the convex portions 60 from the surface of thetransfer body 30. This forms the desired pattern of the dispersingelement 31 on the surface of the transfer body 30. Then, the transferbody 30 on which this desired pattern has been formed is brought intocontact with the board 40, thus ensuring transferring the desiredpattern to the board 40 (see FIG. 5 and FIG. 6B). The method forapplying the dispersing element 31 over the surface of the transfer body30 is not specifically limited as long as the method can uniformly applythe dispersing element 31 over the surface of the transfer body 30.

The conductive pattern in the structure with the conductive pattern ispreferably an antenna. The conductive pattern may be formed into a meshshape. The conductive pattern preferably has the wire width of 1 μm ormore to 1000 μm or less.

The method for manufacturing the structure with the conductive patternpreferably further includes a step of forming the solder layer on a partof the surface of the conductive pattern. Since the firing process ofthe copper decomposes the organic binder contained in the applicationfilm, the wettability of the solder becomes high in the surface of theobtained conductive pattern and the solder layer can be easily formed.

The method for manufacturing the structure with the conductive patternpreferably solders an electronic component on the conductive pattern viathe solder layer by reflow method.

The method for manufacturing the structure with the conductive patternperforms the firing process by plasma firing method that generatesplasma under the atmosphere containing reducing gas or light irradiationmethod, and this allows using a material having a low heat resistancefor the structure.

Additionally, the method for manufacturing the structure with theconductive pattern performing the firing process decomposes the organicmatter contained in the dispersing element, in addition to the reductionof the copper oxide and the firing of the copper particles. Accordingly,an increase in resistivity is prevented, the organic matter and an oxidefilm are removed from the surface of the conductive film, and thesoldering performance can be improved. The firing process decomposes theorganic component, such as the dispersion medium, which deteriorates thesoldering performance. Accordingly, the wettability of the solder to theconductive film is enhanced, making the soldering easy. Accordingly, thestructure with the conductive pattern including the conductive filmexcellent in soldering performance can be obtained. To decompose theorganic component in the conductive film, especially the firing processthat generates plasma under the atmosphere containing the reducing gasis more preferred.

Next, the following further describes the components of the dispersingelement according to the first to the third embodiments in detail.

[Dispersing Element]

Next, the following describes states of the copper oxide and thedispersing agent in the copper oxide ink as the dispersing element withreference to FIG. 8. FIG. 8 is a schematic diagram illustrating arelationship between the copper oxide and phosphoric acid ester saltaccording to the embodiment.

As illustrated in FIG. 8, in a dispersing element 1, for example,phosphoric acid ester salt 3 as an example of a phosphorus-containingorganic matter as the dispersing agent surrounds copper oxide 2 as anexample of the copper oxide orientating phosphoruses 3 a inside andester salts 3 b outside. Since the phosphoric acid ester salt 3 exhibitsan electrical insulating property, electrical conduction with theadjacent copper oxide 2 is interfered. The phosphoric acid ester salt 3reduces the aggregation of the dispersing element 1 by an effect ofsteric hindrance.

Accordingly, the copper oxide 2 is a semiconductor and has a conductiveproperty but is covered with the phosphoric acid ester salt 3 exhibitingthe electrical insulating property. Accordingly, the dispersing element1 exhibits the electrical insulating property and can ensure insulationbetween conductive pattern regions (described later) adjacent to bothsides of the dispersing element 1 in the cross-sectional surface view(the cross-sectional surface taken along the top-down directionillustrated in FIGS. 2A-2D).

Meanwhile, in the conductive pattern region, a part of the region of theapplication film containing the copper oxide and thephosphorus-containing organic matter is irradiated with light andreduces the copper oxide to the copper in this part of the region. Thecopper produced by thus reducing the copper oxide is referred to asreduced copper. The phosphorus-containing organic matter is denatured tophosphorus oxide in this part of the region. In the phosphorus oxide, anorganic matter, such as the above-described ester salt 3 b, isdecomposed by heat, such as laser, and thus does not exhibit anelectrical insulating property.

As illustrated in FIG. 8, with the use of the copper oxide 2, heat, suchas laser, changes the copper oxide into the reduced copper and sintersthe copper oxide 2 to integrate the adjacent copper oxides 2.Accordingly, the region having the excellent electrical conductivity(hereinafter referred to as “conductive pattern region”) can be formed.

In the conductive pattern region, a phosphorus element remains in thereduced copper. The phosphorus element is present as at least one of anelemental phosphorus alone, phosphorus oxide, and aphosphorus-containing organic matter. The thus remaining phosphoruselement is present segregated in the conductive pattern region and thereis no possibility of an increase in resistance of the conductive patternregion.

[Copper Oxide]

In the embodiment, the copper oxide is used as one metal oxidecomponent. As the copper oxide, cuprous oxide (Cu₂O) is preferred. Thisis because the reduction of the cuprous oxide is easy among metaloxides, and further the use of microparticles facilitates sintering.Additionally, in terms of the price, the copper is inexpensive comparedwith noble metals, such as silver, and is advantageous in migration.

The dispersing element according to the embodiment contains the copperoxide particles having the average secondary particle diameter of 1 nmor more to 500 nm or less.

Although not specifically limited, the average secondary particlediameter of the copper oxide is preferably 500 nm or less, morepreferably 200 nm or less, and further preferably 80 nm or less. Theaverage secondary particle diameter of the copper oxide is preferably 1nm or more, more preferably 5 nm or more, further preferably 10 nm ormore, and especially preferably 15 nm or more. Here, the averagesecondary particle diameter refers to an average particle diameter ofaggregates (secondary particles) formed of a collection of a pluralityof primary particles.

This average secondary particle diameter of 500 nm or less tends tofacilitate formation of a fine pattern on the board and therefore ispreferred. The average secondary particle diameter of 1 nm or moreimproves long-term storage stability of the copper oxide ink as thedispersing element and therefore is preferred. The average secondaryparticle diameter of the copper oxide can be measured by cumulant methodusing, for example, FPAR-1000 manufactured by OTSUKA ELECTRONICS.

The preferable range of the average primary particle diameter of thecopper oxide needs to be a low temperature further from perspectives ofdenseness and an electrical characteristic of the metal obtained byperforming a reduction treatment on the copper oxide and further from aperspective of reducing damage given to the board considering the use ofa resin board of the firing condition. In view of this, the averageprimary particle diameter is preferably 100 nm or less, more preferably50 nm or less, and further preferably 20 nm or less. The average primaryparticle diameter of 100 nm or less can reduce input energy so as not todamage the board in a firing process described later. While the lowerlimit value of the average primary particle diameter of the cuprousoxide is not especially restricted, in terms of ease of handling, 1 nmor more is preferred and 5 nm or more is more preferred. Thus, anincrease in usage of the dispersing agent to keep the dispersionstability due to the excessively small particle diameter is reduced andthe firing process becomes easy. The average primary particle diametercan be measured with a transmission electron microscope or a scanningelectron microscope.

The copper oxide in the dispersing element is easily reduced by plasmatreatment, heat treatment at 100° C. or more, or light treatment andturns into metal, and obtains a conductive property through sintering.The copper oxide further works as a binder to the added copper particlesto be integrated, thus contributing to low resistivity and improvementin strength. Note that in the embodiment, the average particle diameterof the cuprous oxide particles does not affect the crack preventingeffect brought by the copper particles having the wire shapes, thedendritic shapes, and the scaly shapes described later.

As the cuprous oxide, commercially available cuprous oxide may be usedor synthesized cuprous oxide may be used. There is provided a commercialproduct manufactured by RMML Co., Ltd. having an average primaryparticle diameter of 5 to 50 nm. The synthetization method includes thefollowing.

(1) A heating and reduction method adds water and copper acetylacetonatecomplex in polyol solvent, once heats and dissolves an organic coppercompound, and then adds water required for reaction and further thetemperature is increased to heat the solvent at a reduction temperatureof organic copper.

(2) A method heats an organic copper compound(copper-N-nitrosophenylhydroxyamine complex) at a high temperaturearound 300° C. in an inert atmosphere under presence of a protectingmaterial, such as hexadecylamine.

(3) A method reduces copper salt dissolved in water solution withhydrazine.

Among these methods, the operation of the method (3) is simple andcuprous oxide having a small average particle diameter is obtained andtherefore is preferred.

Since the obtained cuprous oxide is a soft aggregate, a copper oxidedispersing element dispersed into a dispersion medium is manufacturedand used for printing and application. Synthesized solution and thecuprous oxide are separated after ending the synthetization, and it isonly necessary to use the known method, such as centrifugation.Additionally, a dispersing agent and a dispersion medium described laterare added to the obtained cuprous oxide, and the product is stirred anddispersed by the known method, such as a homogenizer. There may be caseswhere the dispersion is difficult and the dispersion is insufficientdepending on the dispersion medium. In such cases, as one example, afterdispersion using alcohols that facilitate dispersion, for example,butanol and the like as the dispersion medium, the product issubstituted by a desired dispersion medium and concentrated to a desiredconcentration. One example of the method includes a method of repetitionof a concentration with a UF membrane, dilution with a desireddispersion medium, and concentration. The copper oxide dispersingelement thus obtained may be mixed with copper particles and the like bya method described later and can be provided as the dispersing elementof the embodiment. This dispersing element is used for printing andapplication.

[Copper Particles]

The dispersing element according to the second embodiment contains thecopper particles having the particle diameter of 0.1 μm or more to 100μm or less.

The dispersing element according to the third embodiment contains atleast one kind of the copper particles having the shapes extending inone direction, the dendritic shapes, or the flat shapes.

The reasons for using the copper particles for such a dispersing elementare as follows. Since the copper particles are metal identical to metalcopper obtained through reduction of cuprous oxide, copper leaching andformation of an intermetallic compound do not become problems, andelectrical conductivity of a conductive pattern obtained finally issatisfactory and the mechanical strength is sufficient.

The average particle diameter of the particles having the shapesextending in one direction and the particles having the dendritic shapesis an average grain diameter (median diameter, mass basis, D50) measuredusing a particle size distribution measurement device using a laserdiffraction scattering method. The average primary particle diameter ofthe particles having the flat shapes is a diameter of a circle when itsprincipal surface is regarded as this circle having an equal area.

The particle diameters of the copper particles only need to bedetermined in accordance with the shape and the size of the pattern inthe range of the embodiment. For example, in the case where the patternis configured of lines, the particle diameter may be determined inaccordance with their thicknesses and pitches. The particle diameters ofthe copper particles only need to be determined considering the methodfor forming an application film, that is, the printing method or theapplication method.

Especially in screen-printing, it is important to cause the componentscontained in the dispersing element, especially, the copper particles topass through so as not to get stuck in a screen mesh, and the particlediameter needs to be selected considering a mesh size of a plate. In thecase where the particles are excessively large, the particles get stuckin the screen mesh and cause problems that an exit of the particlesgenerates pinholes and smoothness of the surface of the application filmis deteriorated. Especially, when a pattern of the application film isconfigured of narrow lines, a mesh with the large number of meshes isused for a screen, and dimensions of the openings decrease as a result;therefore, a breaking of a wire due to the pinhole caused by cloggingbecomes a problem.

As the copper particles, except for ones made of only the metal copper,ones whose surfaces are coated with copper oxide (cuprous oxide orcupric oxide) or dissimilar metal or its oxide, such as silver or silveroxide, may be used. The use of these metals also sufficiently providesthe effect of reducing cracks. That is, even when the surfaces of thecopper particles are coated with the copper oxide, the silver oxide, orthe like, the copper oxide, the silver oxide, or the like is easilyreduced during firing and therefore the conductivity of the conductivefilm can be maintained.

As the copper particles according to the embodiment, commerciallyavailable copper particles may be used or synthesized copper particlesmay be used.

Examples of the commercial product can include electrolytic copperpowder EAZ-2T manufactured by MITSUI MINING & SMELTING CO., LTD. as thecopper particles having the shapes extending in one direction,electrolytic copper powder EAX-2 manufactured by MITSUI MINING &SMELTING CO., LTD. as the dendritic-shaped copper particles, and 1400YPmanufactured by MITSUI MINING & SMELTING CO., LTD. as the copperparticles having the flat shapes.

[Copper Particle Mass Ratio]

In the dispersing element according to the second and the thirdembodiments, the mass ratio of the copper particles to the mass of thecopper oxide particles (hereinafter referred to as copper particle massratio) is preferably 0.5 or more to 10 or less, more preferably 1.0 ormore to 7.0 or less, further preferably 1.5 or more to 6.0 or less, andespecially preferably 2.0 or more to 5.0 or less. With the copperparticle mass ratio within this range, the cuprous oxide is abundantlypresent; therefore, the bonding between the copper particles obtainedthrough reduction becomes sufficient, thus increasing the mechanicalstrength of the conductive film after firing. The crack reducing effectbrought by the copper particles obtained through the reduction issufficiently provided.

The copper particle mass ratio of the dispersing element containingother metal particles is determined by the sum with the copperparticles, and the copper particle mass ratio of the dispersing elementcontaining other metal oxide particles is determined by the sum with thecopper oxide.

[Dispersing Agent]

The following describes the dispersing agent. An example of thedispersing agent includes a phosphorus-containing organic matter. Thephosphorus-containing organic matter may adsorb to the copper oxide andin this case reduces aggregation by the effect of steric hindrance. Thephosphorus-containing organic matter is a material exhibiting theelectrical insulating property in the insulating region. Thephosphorus-containing organic matter may be a single molecule or may bea mixture of a plurality of kinds of molecules.

The dispersing agent has an acid value preferably 20 or more to 130 orless. By thus limiting the range of the acid value of the dispersingagent effectively improves the dispersion stability of the dispersingelement.

The mass ratio of the organic compound to the mass of the copper oxideparticles in the dispersing element is preferably 0.0050 or more to 0.30or less.

A number average molecular weight of the dispersing agent is notespecially restricted but is preferably 300 or more, more preferably 500or more, and further preferably 1000 or more. The number averagemolecular weight of the dispersing agent is not especially restricted,but is preferably 30000 or less, more preferably 20000 or less, andfurther preferably 10000 or less. The number average molecular weight of300 or more tends to exhibit an excellent insulating property andincrease the dispersion stability of the obtained dispersing element,and the number average molecular weight of 30000 or less facilitatesfiring. As a structure, phosphate ester of a high molecular weightcopolymer having a group having affinity to copper oxide is preferred.For example, the structure of the chemical formula (1) adsorbs thecopper oxide, especially the cuprous oxide, and is excellent inadhesiveness to the board and therefore is preferred.

The phosphorus-containing organic matter is preferred to be easilydecomposed or vaporized by light and heat. The use of the organic mattereasily decomposed or vaporized by light and heat is less likely toremain a residue of the organic matter after firing, thereby ensuringobtaining the conductive pattern region having low resistivity.

Although not limited, a decomposition temperature of thephosphorus-containing organic matter is preferably 600° C. or less, morepreferably 400° C. or less, and further preferably 200° C. or less.Although not limited, a boiling point of the phosphorus-containingorganic matter is preferably 300° C. or less, more preferably 200° C. orless, and further preferably 150° C. or less.

Although an absorption property of the phosphorus-containing organicmatter is not limited, the phosphorus-containing organic matter canpreferably absorb light used for firing. For example, with the use oflaser light as a light source for firing, the use of thephosphorus-containing organic matter that can absorb light with itsemission wavelength of, for example, 355 nm, 405 nm, 445 nm, 450 nm, 532nm, and 1056 nm is preferred. With a board made of resin, thewavelengths of 355 nm, 405 nm, 445 nm, and 450 nm are especiallypreferred.

The known dispersing agents are usable, and examples include amacromolecule having a basic group, such as long-chain polyaminoamideand salt of polar acid ester, unsaturated polycarboxylic acidpolyaminoamide, polycarboxylate of polyaminoamide, long-chainpolyaminoamide and salt of acid polymer, and the like. The examplesinclude acrylic-based polymer, acrylic-based copolymer, modifiedpolyester acid, polyetherester acid, polyether-based carboxylic acid,and macromolecular alkyl ammonium salt, such as polycarboxylic acid,amine salt, amido amine salt, and the like. As such a dispersing agent,a commercially available one is usable.

Examples of the commercial product include DISPERBYK (registeredtrademark)-101, DISPERBYK-102, DISPERBYK-110, DISPERBYK-111,DISPERBYK-112, DISPERBYK-118, DISPERBYK-130, DISPERBYK-140,DISPERBYK-142, DISPERBYK-145, DISPERBYK-160, DISPERBYK-161,DISPERBYK-162, DISPERBYK-163, DISPERBYK-2155, DISPERBYK-2163,DISPERBYK-2164, DISPERBYK-180, DISPERBYK-2000, DISPERBYK-2025,DISPERBYK-2163, DISPERBYK-2164, BYK-9076, BYK-9077, TERRA-204, TERRA-U(manufactured by BYK up to here), FlOWLEN DOPA-15B, FlOWLEN DOPA-15BHFS,FlOWLEN DOPA-22, FlOWLEN DOPA-33, FlOWLEN DOPA-44, FlOWLEN DOPA-17HF,FlOWLEN TG-662C, and FlOWLEN KTG-2400 (manufactured by KYOEISHA CHEMICALCo., LTD. up to here), ED-117, ED-118, ED-212, ED-213, ED-214, ED-216,ED-350, and ED-360 (manufactured by Kusumoto Chemicals, Ltd. up tohere), PLYSURF M208F, PLYSURF DBS (manufactured by DKS Co. Ltd. up tohere), and the like. These products may be used alone, or a plurality ofthese products may be mixed for use.

The required amount of the dispersing agent is proportionate to theamount of copper oxide and adjusted considering the required dispersionstability. The mass ratio of the dispersing agent contained in thedispersing element of the embodiment (dispersing agent mass/copper oxidemass) is from 0.0050 or more to 0.30 or less, preferably 0.050 or moreto 0.25 or less, and more preferably 0.10 or more to 0.23 or less. Theamount of the dispersing agent affects the dispersion stability, thesmall amount of the dispersing agent is likely to aggregate, and thelarge amount of the dispersing agent tends to improve the dispersionstability. Note that when a content proportion of the dispersing agentin the dispersing element of the embodiment is designed to be 35 mass %or less, an influence from a residue derived from the dispersing agentin the conductive film obtained by firing is reduced and the conductiveproperty can be improved.

The dispersing agent preferably has the acid value (mgKOH/g) of 20 ormore to 130 or less. The acid value is more preferably 30 or more to 100or less. The acid value in this range is excellent in dispersionstability and therefore is preferred. Such dispersing agent isespecially effective in the case of the copper oxide having the smallaverage particle diameter. Specifically, the dispersing agent includes“DISPERBYK-102” (acid value: 101), “DISPERBYK-140” (acid value: 73),“DISPERBYK-142” (acid value: 46), “DISPERBYK-145” (acid value: 76),“DISPERBYK-118” (acid value: 36), “DISPERBYK-180” (acid value: 94)manufactured by BYK, and the like.

A difference between an amine value (mgKOH/g) and the acid value of thedispersing agent (amine value−acid value) is preferably −50 or more to 0or less. The amine value indicates a total amount of a free base and abase, and the acid value indicates a total amount of free fatty acid andfatty acid. The amine value and the acid value are measured by a methodcompliant with JIS K 7700 or ASTM D2074. The difference of −50 or moreto 0 or less is excellent in dispersion stability and therefore ispreferred, −40 or more to 0 or less is more preferred, and −20 or moreto 0 or less is further preferred.

[Reductant]

The following describes the reductant. The reductant includes hydrazine,hydrazine hydrate, sodium, carbon, potassium iodide, oxalic acid, ironsulfide (II), sodium thiosulfate, ascorbic acid, tin chloride (II),diisobutylaluminium hydride, formic acid, sodium borohydride, sulfite,and the like. From perspectives of contribution to reduction of copperoxide, especially cuprous oxide, in firing, and ensuring manufacturing acopper film having further low resistance, the use of hydrazine orhydrazine hydrate as the reductant is the most preferable. The use ofhydrazine or hydrazine hydrate can maintain the dispersion stability ofthe dispersing element and can reduce the resistance of the copper film.

The required amount of the reductant is proportionate to the amount ofthe copper oxide and adjusted considering the required reducibility. Themass ratio of the reductant contained in the dispersing element of theembodiment (reductant mass/copper oxide mass) is preferably 0.0001 ormore to 0.10 or less, more preferably 0.0001 or more to 0.05 or less,and further preferably 0.0001 or more to 0.03 or less. The mass ratio ofthe reductant of 0.0001 or more improves the dispersion stability anddecreases the resistance of the copper film. The mass ratio of 0.10 orless improves the long-term stability of the dispersing element.

[Dispersion Medium]

The dispersing element of the embodiment may contain the dispersionmedium (solvent) in addition to the above-described components.

The dispersion medium used for the dispersing elements according to thefirst to the third embodiments are preferably at least one kind selectedfrom the group consisting of terpineol, y-butyrolactone, cyclohexanone,ethanol, propylene glycol, butanol, propanol, ethylene glycol monoethylether acetate and tetralin. Containing two or more kinds of thesedispersion mediums are more preferred.

Since these dispersion mediums have high boiling points, an effect ofimprovement in print continuity is provided. While these dispersionmediums may have a reduction action, when the above-described reductantis contained in the dispersing element, the reductant serves as adispersion medium.

As the dispersion mediums used for the first to the third embodiments,one that can dissolve the dispersing agent is selected from aperspective of dispersion. Meanwhile, from a perspective of forming theconductive pattern using the dispersing element, since volatility of thedispersion medium affects work efficiency, the dispersion medium needsto be suitable for the method for forming the conductive pattern, forexample, printing and application methods. Therefore, the dispersionmedium is selectable from the following solvents according todispersibility and the work efficiencies of the printing and theapplication.

Specific examples of the dispersion medium can include the followingsolvents. Propylene glycol monomethylether acetate,3-methoxy-3-methyl-butyl acetate, ethoxyethyl propionate, propyleneglycol monomethyl ether, propylene glycol monoethyl ether, propyleneglycol monopropyl ether, propylene glycol tertiary butyl ether,dipropylene glycol monomethyl ether, ethylene glycol butyl ether,ethylene glycol ethyl ether, ethylene glycol methyl ether, ethyleneglycol, 1,2-propylene glycol, 1,3-butylene glycol, 2-pentanediol,2-methylpentane-2,4-diol, 2,5-hexanediol, 2,4-heptanediol,2-ethylhexane-1,3-diol, diethylene glycol, hexanediol, octanediol,triethylene glycol, tri-1,2-propylene glycol, glycerol, ethylene glycolmonohexyl ether, diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, ethylene glycol monobutyl acetate, diethylene glycolmonoethyl ether acetate, methanol, ethanol, n-propanol, i-propanol,n-butanol, i-butanol, 2-butanol, t-butanol, n-pentanol, i-pentanol,2-methyl butanol, 2-pentanol, t-pentanol, 3-methoxy butanol, n-hexanol,2-methylpentanol, 1-hexanol, 2-hexanol, 2-ethyl-butanol, 1-heptanol,2-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, 2-octanol,n-nonylalcohol, 2,6-dimethyl-4-heptanol, n-decanol, cyclohexanol,methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol,diacetone alcohol, and the like. Except for these specifically describedsubstances, alcohol, glycol, glycol ether, and glycol esters solventsare usable as the dispersion medium. These substances may be used aloneor a plurality of these substances may be mixed for use. The substanceis selected in consideration of vaporizability, print machinery, andsolvent resistance of a printed board according to the printing method.

As the dispersion medium, monoalcohol with ten carbons or less is morepreferred and eight carbons or less is further preferred. Amongmonoalcohols with eight carbons or less, ethanol, n-propanol,i-propanol, n-butanol, i-butanol, sec-butanol, and t-butanol areespecially suitable in dispersibility, volatility, and viscosity andtherefore are further preferred. These monoalcohols may be used alone ora plurality of these monoalcohols may be mixed for use. To reduce thedecrease in dispersibility of the copper oxide and for further stabledispersion by an interaction with the dispersing agent, the monoalcoholwith eight carbons or less is preferred. Additionally, the selection ofeight carbons or less decreases the resistance value and therefore ispreferred.

However, the boiling point affects the work efficiency of the solvent.The excessively low boiling point makes the volatilization fast;therefore, due to an increase in defect and an increase in cleaningfrequency caused by precipitation of a solid material, the workefficiency is deteriorated. In view of this, the boiling point 40° C. ormore is preferred in the application and the dispenser method, theboiling point 120° C. or more is preferred in the inkjet method, thescreen method, and the offset method, 150° C. or more is more preferred,200° C. or more is further preferred, and as the upper limit of theboiling point, 300° C. or less is preferred from the perspective ofdrying.

[Preparation of Dispersing Element Containing Copper Oxide and Copper]

The dispersing element containing the cuprous oxide and the copperparticle, namely, the dispersing element can be prepared as follows.Copper microparticles and, as necessary, a dispersion medium are mixedwith the above-described copper oxide dispersing element at respectivepredetermined proportions, and a dispersion process is performed using,for example, mixer method, ultrasonic wave method, three-roll method,two-roll method, attritor, homogenizer, banbury mixer, paint shaker,kneader, ball mill, sand mill, rotary and revolutionary mixer, or thelike.

Since the dispersion medium is partially contained in the alreadygenerated copper oxide dispersing element, in the case where thedispersion medium is sufficient by the amount contained in this copperoxide dispersing element, the dispersion medium needs not to be added inthis step, and the dispersion medium only needs to be added in this stepas necessary when the viscosity needs to decrease. Alternatively, thedispersion medium may be added after this step. The dispersion mediumidentical to one added during the manufacturing of the above-describedcopper oxide dispersing element or different from the one may be added.

Besides, according to need, an organic binder, antioxidant, reductant,metal particles, or metal oxide may be added, and as impurities, metal,metal oxide, metal salt, and metal complex may be contained.

Since the wire-shaped, the dendritic-shaped, or the scaly-shaped copperparticles provide the large crack preventing effect, the copperparticles may be used alone or may be added in combination with aplurality of copper particles having spherical shapes, cubic shapes,polyhedron shapes, or the like and another metal, and their surfaces maybe coated with oxide or another metal having a good conductive property,for example, silver.

In the case where one kind or a plurality of metal particles other thancopper having the wire shapes, the dendritic shapes, and the scalyshapes are added, to provide the crack preventing effect similarly tothe copper particles having the similar shapes, the metal particles canbe substituted for a part of the copper particles having the similarshapes or added to the copper particles having the similar shapes foruse; however, a migration, a particle strength, a resistance value,copper leaching, formation of an intermetallic compound, a cost, and thelike need to be considered. Examples of the metal particles other thancopper can include gold, silver, tin, zinc, nickel, platinum, bismuth,indium, and antimony.

As the metal oxide particles, the cuprous oxide can be substituted byoxidized silver, cupric oxide, or the like, or they can be added foruse. However, similarly to the case of the metal particles, a migration,a particle strength, a resistance value, copper leaching, formation ofan intermetallic compound, a cost, and the like need to be considered.The additions of these metal particles and metal oxide particles areusable for adjustments of the sintering, the resistance, the conductorstrength, absorbance during firing with light of the conductive film,and the like. Even when these metal particles and metal oxide particlesare added, the presence of the wire-shaped, the dendritic-shaped, or thescaly-shaped copper particles sufficiently reduces cracks. These metalparticles and metal oxide particles may be used alone or in acombination of two kinds of more, and the shapes are not restricted. Forexample, silver and oxidized silver are expected to bring effects, suchas the decrease in resistance and the decrease in firing temperature.

However, from perspectives of an increase in cost of the silver as noblemetals and the prevention of cracks, the additive amount of the silveris preferably in a range not exceeding those of the wire-shaped, thedendritic-shaped, or the scaly-shaped copper particles. Additionally,since tin is a low price and has a low melting point, tin isadvantageous in its ease of sintering. However, tin tends to increasethe resistance and from the perspective of crack prevention, theadditive amount of the tin is preferably in a range not exceeding thoseof the wire-shaped, dendritic-shaped, or scaly-shaped copper particlesand the cuprous oxide. In a method using light and infrared, such as aflash lamp and laser, cupric oxide acts as light absorber and heat rayabsorbent. However, from perspectives that cupric oxide is less likelyto be reduced compared with cuprous oxide and a peeling from the boardcaused by much gas generation during reduction is prevented, theadditive amount of the cupric oxide is preferably smaller than that ofthe cuprous oxide.

In the embodiment, even when metal other than copper, copper particleshaving shapes other than wire shapes, dendritic shapes, and scalyshapes, or metal oxide other than copper oxide is contained, the crackpreventing effect and the effect of improvement in stability ofresistance over time are provided. However, the additive amounts of themetal other than copper, the copper particles having the shapes otherthan the wire shapes, the dendritic shapes, and the scaly shapes, andthe metal oxide other than copper oxide are preferably smaller thanthose of the copper particles having the wire shapes, the dendriticshapes, and the scaly shapes, and the copper oxide. Additionally,proportions of adding the metal other than copper, the copper particleshaving the shapes other than the wire shapes, the dendritic shapes, andthe scaly shapes, and the metal oxide other than copper oxide to thewire-shaped, the dendritic-shaped, or the scaly-shaped copper particlesand the copper oxide are 50% or less, more preferably 30% or less, andfurther preferably 10% or less.

[Details of Structure with Conductive Pattern]

The following specifically describes each configuration of the structurewith the conductive pattern 10 according to the embodiment. Note thateach configuration is not limited to specific examples described below.

The method for manufacturing the structure with the conductive patternaccording to the embodiment includes a step of applying the dispersingelement according to the embodiment over the board to form theapplication film and a step of irradiating the application film withlaser light to form the conductive pattern on the board.

The method for manufacturing the structure with the conductive patternaccording to the embodiment includes a step of applying the dispersingelement over the board in a desired pattern to form the application filmand a step of performing the firing process on the application film toform the conductive pattern on the board. The method according to theembodiment allows directly forming the desired pattern on the board withapplication liquid; therefore, compared with the conventional method ofusing a photoresist, productivity can be improved.

[Application Method of Dispersing Element over Board]

The following describes the application method using the copper oxideink as the dispersing element. The application method is notspecifically limited, and a printing method, such as an aerosol method,a screen-printing, direct intaglio printing, intaglio offset printing,flexography, and offset printing, a dispenser drawing method, and thelike are usable. The application method, such as a die coat, a spincoat, a slit coat, a bar coat, a knife coat, a spray coat, and a dipcoat are usable.

[Board]

The board used in the embodiment has a surface forming the applicationfilm and may have a plate shape or may be a three-dimensional object.The board in the embodiment means a board material of a circuit boardsheet to form a wiring pattern, a casing material of a casing withwiring, or the like. Examples of the casing include a casing for anelectrical device, such as a mobile phone terminal, a smart phone, smartglasses, a television, and a personal computer. Other examples of thecasing in the automotive field include a dashboard, an instrument panel,a steering wheel, a chassis, and the like.

The board used for the embodiment is not specifically limited and madeof an inorganic material or an organic material.

Examples of the inorganic material include a glass, such as a soda limeglass, a non-alkali glass, a borosilicate glass, and a quartz glass, anda ceramic material, such as alumina.

The organic material includes a high-polymer material, a paper, and thelike. As the high-polymer material, a resin film is usable. The resinfilm can include polyimide (PI), polyethylene terephthalate (PET),polyethersulfone (PES), polyethylene naphthalate (PEN), polyester,polycarbonate (PC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB),polyacetal (POM), polyarylate (PAR), polyamide (PA), polyamide imide(PAI), polyetherimide (PEI), polyphenylene ether (PPE),modified-polyphenyleneether (m-PPE), polyphenylene sulfide (PPS),polyether ketone (PEK), polyphthalamide (PPA), polyether nitrile (PEN),polybenzimidazole (PBI), polycarbodiimide, polysiloxane,polymethacrylamide, nitrile rubber, acrylic rubber, polyethylenetetrafluoride, epoxy resin, phenolic resin, melamine resin, urea resin,polymethyl methacrylate (PMMA), polybutene, polypentene,ethylene-propylene copolymer, ethylene-butene-diene copolymer,polybutadiene, polyisoprene, ethylene-propylene-diene copolymer, butylrubber, polymethylpentene (PMP), polystyrene (PS), styrene-butadienecopolymer, polyethylene (PE), polyvinyl chloride (PVC), polyvinylidenefluoride (PVDF), polyether ether ketone (PEEK), phenolic novolac,benzocyclobutene, polyvinylphenol, polychloroprene, polyoxymethylene,polysulfone (PSF), polyphenyl sulfone resin (PPSU), cycloolefin polymer(COP), acrylonitrile butadiene styrene resin (ABS), acrylonitrilestyrene resin (AS), nylon resin (PA6, PA66), polybutylene terephthalateresin (PBT), polyether sulfone resin (PESU), polytetrafluoroethyleneresin (PTFE), polychlorotrifluoroethylene (PCTFE), silicone resin, andthe like. Especially, PI, PET, and PEN are preferred from perspectivesof flexibility and a cost.

The paper includes a western paper, such as a high-quality paper, amedium-quality paper, a coated paper, a cardboard, and a corrugatedcardboard using general pulp as a raw material, and a paper usingcellulose nanofiber as a raw material. In the case of the paper, a paperproduced by dissolving a high-polymer material or a paper produced byimpregnating and hardening a sol-gel material is usable. These materialsmay be used by pasting, such as lamination. Examples of the paperinclude a composite base material, such as a paper phenol base material,a paper epoxy base material, a glass composite base material, and aglass epoxy base material, a Teflon (registered trademark) basematerial, an alumina base material, Low Temperature and Low-humidityCo-fired Ceramics (LTCC), a silicon wafer, and the like.

The board can be designed to have a thickness of, for example, 1 μm to10 mm, and 25 μm to 250 μm is preferred. The board having the thicknessof 250 μm or less allows a weight reduction of a manufactured electronicdevice, space saving, and flexibility and therefore is preferred. Withthe board being a casing, its thickness can be designed to be, forexample, 1 μm to 10 mm, and 200 μm to 5 mm is preferred. It has becomeapparent by the inventors that selecting this range develops themechanical strength and the heat resistance after molding.

[Formation of Conductive Pattern]

The method for forming the conductive pattern includes 1) a method ofmanufacturing a pattern using the above-described printing method andthen firing the pattern and 2) a method that coats the dispersingelement over the whole surface of the board and manufactures a patternthere so as to be a specific pattern by laser drawing. In both 1) and2), a part of the copper oxide is not reduced but remains on the boardside and this improves adhesiveness between the conductive pattern andthe board, and this is preferred. The conductive pattern is a wiring,and having the wiring width of 0.5 μm or more to 10000 μm or less ispreferred, 1 μm or more to 1000 μm or less is more preferred, and 1 μmor more to 500 μm or less is further preferred. The conductive patternmay be formed into a mesh shape. The mesh shape refers to wiring in agrid shape that increases transmittancy and becomes transparent andtherefore is preferred.

[Firing of Dispersing Element]

As long as the conductive film that provides the effects of the presentinvention can be formed, the method for the firing process is notspecifically limited, and the specific examples include a method ofusing an incinerator, a plasma firing method, a light firing method, andthe like. In the laser irradiation in the light firing, the applicationfilm is formed with the copper oxide ink as the dispersing element andthe application film is irradiated with laser, thus ensuring performingthe firing of the copper particles and patterning at once. Anotherfiring method prints a desired pattern with the dispersing element andfires the desired pattern, thus ensuring obtaining the conductivepattern. When the conductive pattern is manufactured, a part of thecuprous oxide is not reduced but remains on the contact surface with theboard, and this improves the adhesiveness between the conductive patternand the board and therefore is preferred.

[Kiln]

In the embodiment, the firing method using the kiln reduces the copperoxide into the copper and sinters the copper and therefore fires theapplication film by heat at 100° C. or more, preferably 150° C. or more,and more preferably 200° C. or more.

The method of firing with the kiln or the like, which is likely to beaffected by oxygen, preferably processes the application film of thedispersing element under a non-oxidizing atmosphere. In the case wherethe copper oxide is less likely to be reduced only by the organiccomponent contained in the dispersing element, firing under a reducingatmosphere is preferred. The non-oxidizing atmosphere is an atmospherenot containing oxidized gas, such as oxygen, for example, an atmospherefilled with inert gas, such as nitrogen, argon, helium, and neon. Whilethe reducing atmosphere refers to an atmosphere where reducing gas, suchas hydrogen or carbon monoxide, is present, the reducing gas may be usedmixed with inert gas. The application film of the dispersing element maybe fired with the inside of the sealed kiln filled with these gases orwhile the gases are continuously flown into the kiln. The firing may beperformed under a pressurized atmosphere or a depressurized atmosphere.

[Plasma Firing Method]

Compared with the method using the kiln, the plasma method of theembodiment allows the process at a lower temperature, and is one of abetter method as the firing method in the case of the use of a resinfilm having low heat resistance as a base material. Since the organicmatter and the oxide film on the pattern surface are removable byplasma, this method is also advantageous in that a satisfactorysoldering performance can be ensured. Specifically, the method flowsreducing gas or mixed gas of reducing gas and inert gas into a chamber,generates plasma with a microwave, and uses active species generated bythis as a heating source necessary for reduction or sintering andfurther decomposition of the organic matter contained in the dispersingagent and the like to obtain the conductive film.

Especially in the metal part, deactivation of the active species islarge, the metal part is selectively heated, and the temperature of theboard itself is less likely to increase, the plasma firing method isapplicable to a resin film as the board. The dispersing element containsthe copper as metal, and as the firing proceeds, the copper oxidechanges into the copper; therefore, the heating is promoted in only thepattern part. When the organic matter in the dispersing agent or thebinder component remains in the conductive pattern, while the organicmatter hinders the sintering and the resistance tends to increase, theplasma method has a large effect of removing the organic matter in theconductor pattern. The plasma method can remove the organic matter andthe oxide film on the surface of the application film and therefore isadvantageous in that the soldering performance of the conductive patterncan be effectively improved.

As the reducing gas component, hydrogen and the like, and as the inertgas component, nitrogen, helium, argon, and the like are usable. Thesesubstances may be used alone or the reducing gas component and the inertgas component may be mixed at any proportion for use. Additionally, twoor more kinds of the inert gas components may be mixed for use.

The plasma firing method can adjust a microwave input power, anintroduced gas flow rate, a chamber internal pressure, a distance from aplasma generation source to a process sample, a process sampletemperature, and processing time, and adjustment of these items canchange intensity of the process. Therefore, needless to say about aboard of an inorganic material, achieving the optimization of theadjustment items allows using a thermosetting resin film of an organicmaterial, a paper, a thermoplastic resin film having a low heatresistance, for example, PET and PEN as the board, and the conductivefilm having the low resistance can be obtained. Note that the optimalconditions differ depending on the device structure and a kind of thesample and therefore are adjusted according to the situation.

[Light Firing Method]

As the light firing method of the embodiment, a flash light method usinga discharge tube of, for example, xenon as the light source and a laserlight method are applicable. These methods are methods that expose thedispersing element with light at a large intensity for a short period toincrease the temperature of the dispersing element applied over theboard to be a high temperature in a short period and fires thedispersing element, and are methods that reduce the copper oxide, sinterthe copper particles, integrate the copper oxide and the copperparticles, and decompose the organic component to form the conductivefilm. Because of the short firing period, the methods are methods inwhich damage to the board is small and are applicable to a resin filmboard having a low heat resistance.

The flash light method is a method that instantly discharges electriccharges stored in a condenser using the xenon discharge tube, generatesa large amount of pulse light, and irradiates the dispersing elementformed on the board with the pulse light to instantly heat the copperoxide at a high temperature and changes the copper oxide into theconductive film. The amount of exposure is adjustable by opticalintensity, a light emission period, a light irradiation interval, andthe number of times. When optical transparency of the board is large,the conductive pattern with the dispersing element can be formed on theresin board having the low heat resistance, such as PET and PEN, apaper, and the like.

Although the light emission source differs, the use of the laser lightsource allows obtaining the similar effects. In the case of laser, inaddition to the adjustment items of the flash light method, a wavelengthis freely selected, and is selectable in consideration of an opticalabsorption wavelength of the dispersing element with which the patternis formed and an absorption wavelength of the board. Additionally, anexposure by beam scan is possible, and this method features in that theexposure range is easily adjusted, such as a selection of an exposure tothe whole board surface or a partial exposure. As the kinds of thelaser, yttrium.aluminum.garnet (YAG), yttrium vanadate (YVO), ytterbium(Yb), semiconductor laser (GaAs, GaAlAs, GaInAs), carbonic acid gas, andthe like are usable. Not only a fundamental wave, higher harmonics maybe extracted as necessary for use.

Especially, in the case of using laser light, its emission wavelength ispreferably 300 nm or more to 1500 nm or less. For example, 355 nm, 405nm, 445 nm, 450 nm, 532 nm, 1056 nm, and the like are preferred. For theboard and the casing made of resin, a laser wavelength of 355 nm, 405nm, 445 nm, 450 nm, and 532 nm are especially preferred in terms of anabsorption region of the copper-oxide-containing layer of theembodiment. The use of the laser allows freely manufacturing a desiredpattern into a plane and a solid body.

The surface roughness of the surface of the conductive layer or theconductive pattern is preferably 500 nm or more to 4000 nm or less, morepreferably 750 nm or more to 3000 nm or less, and further preferably1000 nm or more to 2000 nm or less. The surface roughness in this rangefacilitates adhesion of the solder layer on the conductive pattern andincreases the adhesiveness between the conductive pattern and the solderlayer.

[Formation of Solder Layer to Conductive Pattern]

In the structure with the conductive pattern manufactured using thedispersing element according to the embodiment, the dispersing agent andthe dispersion medium, which degrade the soldering performance, aredecomposed in the step of the firing process; therefore, the structurewith the conductive pattern is advantageous in that when a bonded body(for example, an electronic component or the like) is soldered to theconductive pattern, adhesion of the melted solder is facilitated. Here,the solder is alloy mainly containing lead and tin and includeslead-free solder not containing lead. The conductive pattern accordingto the embodiment includes the hollow wall (void). Accordingly, theentrance of the solder into this void increases the adhesiveness betweenthe conductive pattern and the solder layer.

The grain sizes of the coppers contained in the conductive pattern andthe conductive layer are preferably 0.1 μm or more to 100 μm or less,further preferably 0.5 μm or more to 50 μm or less, and especiallypreferably 1.0 μm or more to 10 μm or less. This increases theadhesiveness between the conductive pattern and the solder layer.

In the embodiment, the electronic component is at least one kind amongan active component, such as a semiconductor, an integrated circuit, adiode, and a liquid crystal display, a passive component, such as aresistor and a capacitor, and a mechanism component, such as aconnector, a switch, an electric wire, a heat sink, and an antenna.

The solder layer is formed to the conductive pattern preferably by areflow method. The reflow method solders by first applying a solderpaste (solder cream) on the surface of a part of the conductive patternregion formed in (j) of FIG. 3 and (l) of FIG. 4, for example, a land.The solder paste is applied by, for example, contact printing using ametal mask and a metal squeegee. This forms the solder layer on a partof the surface of the conductive pattern. That is, after the step of (j)of FIG. 3, the structure with the conductive pattern in which the solderlayer is formed on a part of the surface of the conductive pattern inthe superficial layer is obtained. After the step of (l) of FIG. 4, thestructure with the conductive pattern in which the solder layer isformed on a part of the surface of the conductive pattern is obtained.An area of a part of the surface of the conductive pattern on which thesolder layer is formed is not specifically limited, and the area onlyneeds to be an area that the conductive pattern can be bonded to theelectronic component.

(Bonding of Electronic Component)

Next, the electronic component is placed on the conductive board suchthat the bonded portion of the electronic component is brought intocontact with a part of the applied solder paste (solder layer).Afterwards, the conductive board on which the electronic component isplaced is passed through a reflow furnace for heating, and a part of theconductive pattern region (such as the land) and the bonded portion ofthe electronic component are soldered. FIGS. 9A-9B are top views of thestructure with the conductive pattern on which the solder layersaccording to the embodiment are formed. FIG. 9A is a photograph of thestructure with the conductive pattern on which the solder layers areformed, and FIG. 9B illustrates a schematic diagram of the structurewith the conductive pattern.

As illustrated in FIGS. 9A-9B, on the board 11 having flexibility, aconductive pattern B formed by firing the copper oxide ink as thedispersing element is formed. Solder layers 20 are formed on the surfaceof the conductive pattern B. The solder layer 20 appropriately soldersthe conductive pattern B and a conducting wire 90, and the conductivepattern B and an electronic component 91 are appropriately coupled viathe conducting wire 90.

The method for manufacturing the structure with the conductive patternaccording to the embodiment fires the copper oxide ink as the dispersingelement to form the conductive pattern; therefore, the organic bindercontained in the dispersing element is decomposed. Accordingly, theobtained conductive pattern increases the wettability of the solder, andthis allows easily forming the solder layer on the surface of theconductive pattern. In view of this, the electronic component can besoldered. Consequently, a failure of the solder layer, which bonds theconductive pattern region and the bonded portion of the electroniccomponent, is prevented, and the structures with the conductive patternsto which the electronic component are soldered can be manufactured at ahigh yield.

Additionally, with the method for manufacturing the structure with theconductive pattern according to the second embodiment, the applicationfilm formed using the dispersing element containing copper oxideparticles having the particle diameter of 1 nm or more to 50 nm or less,the copper particles having the particle diameters of 0.1 μm or more to100 μm or less, and the organic compound having the phosphate groupexhibits the high wettability of the solder. This allows reducing astate where, after the metal surface is coated with the melted solder,the solder shrinks, and a considerably thin part is formed in thesolder, namely, dewetting. Consequently, a failure of the solder bondingportion bonded to the conductive film and the bonded portion of theelectronic component can be prevented and the boards with the electroniccomponents can be manufactured at a high yield.

WORKING EXAMPLES

While the following further specifically describes the present inventionthrough working examples and comparative examples, the present inventionis not limited to these working examples and comparative examples.

Experimental Example 1 [Hydrazine Quantitative Method]

Hydrazine was quantitated by standard addition method.

Hydrazine of 33 μg, a surrogate substance (hydrazine ¹⁵N₂H₄) of 33 μg,and acetonitrile solution with 1% of benzaldehyde of 1 ml were added toa sample (copper nano ink) of 50 μL. Finally, phosphoric acid of 20 μLwas added, and GC/MS measurement was performed after the elapse of fourhours.

Similarly, hydrazine of 66 μg, a surrogate substance (hydrazine ¹⁵N₂H₄)of 33 μg, and acetonitrile solution with 1% of benzaldehyde of 1 ml wereadded to a sample (copper nano ink) of 50 μL. Finally, phosphoric acidof 20 μL was added, and GC/MS measurement was performed after the elapseof four hours.

Similarly, hydrazine of 133 μg, a surrogate substance (hydrazine ¹⁵N₂H₄)of 33 μg, and acetonitrile solution with 1% of benzaldehyde of 1 ml wereadded to a sample (copper nano ink) of 50 μL. Finally, phosphoric acidof 20 μL was added, and GC/MS measurement was performed after the elapseof four hours.

Finally, without adding hydrazine, a surrogate substance (hydrazine¹⁵N₂H₄) of 33 μg and acetonitrile solution with 1% of benzaldehyde of 1ml were added to a sample (copper nano ink) of 50 μL. Finally,phosphoric acid of 20 μL was added, and GC/MS measurement was performedafter the elapse of four hours.

A peak area value of the hydrazine was obtained from a chromatogram ofm/z=207 of the GC/MS measurements of the four samples. Next, the peakarea value of the surrogate was obtained from mass chromatogram ofm/z=209. A weight of the added hydrazine/weight of the added surrogatesubstance was plotted on an x-axis and the peak area value ofhydrazine/peak area value of the surrogate substance was plotted on ay-axis to obtain a calibration curve by standard addition method.

A value of a Y intercept obtained from the calibration curve was dividedby the weight of the added hydrazine/weight of the added surrogatesubstance to obtain the weight of hydrazine.

[Particle Diameter Measurement]

Using FPAR-1000 manufactured by OTSUKA ELECTRONICS, an average secondaryparticle diameter of the copper oxide ink as the dispersing element wasmeasured by cumulant method.

Working Example 1

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by an externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of54.8 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 907 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing a homogenizer to obtain cuprous oxide dispersion liquid (copperoxide ink) of 1365 g.

The dispersion liquid was properly dispersed. The content proportion ofthe cuprous oxide was 20%, and the average secondary particle diameterwas 22 nm. The hydrazine proportion was 3000 ppm.

Working Example 2

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by the externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of54.8 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 907 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing the homogenizer to obtain cuprous oxide dispersion liquid of 1365g. Further, the dispersion liquid was bubbled with air.

The dispersion liquid was properly dispersed. The content proportion ofthe cuprous oxide was 20%, and the average secondary particle diameterwas 25 nm. The hydrazine proportion was 700 ppm.

Working Example 3

Hydrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) of 1.5 gwas put in the dispersion liquid of 98.5 g obtained in Working Example1.

The dispersion liquid was properly dispersed. The content proportion ofthe cuprous oxide was 20%, and the average secondary particle diameterwas 29 nm. The hydrazine proportion was 18000 ppm.

Working Example 4

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by the externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of1.37 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 960 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing a homogenizer to obtain cuprous oxide dispersion liquid (copperoxide ink) of 1365 g.

The dispersion liquid was properly dispersed. The content proportion ofthe cuprous oxide was 20%, and the average secondary particle diameterwas 32 nm. The hydrazine proportion was 3000 ppm.

Working Example 5

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by the externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of82.2 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 880 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing the homogenizer to obtain cuprous oxide dispersion liquid (copperoxide ink) of 1365 g.

The dispersion liquid was properly dispersed. The content proportion ofthe cuprous oxide was 20%, and the average secondary particle diameterwas 32 nm. The hydrazine proportion was 3000 ppm.

Comparative Example 1

Cuprous oxide (MP-Cu2O-25 manufactured by EM Japan) of 4 g,DisperBYK-145 (manufactured by BYK) of 0.8 g, and SURFLON 5611(manufactured by SEIMI CHEMICAL) of 0.2 g were added to ethanol(manufactured by KANTO CHEMICAL CO., INC.) of 15 g, and the product wasdispersed using the homogenizer to obtain cuprous oxide dispersionliquid of 20 g.

It was observed that the copper oxide particles were partiallyaggregated in the dispersion liquid. The content proportion of thecuprous oxide was 20%, and the average secondary particle diameter was190 nm. The hydrazine proportion was 0 ppm.

Comparative Example 2

Hydrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) of 3 g wasput in the dispersion liquid of 97 g obtained in Working Example 1.

The copper oxide particles were aggregated in the dispersion liquid,failing to produce ink. The content proportion of the cuprous oxide was20%. The hydrazine proportion was 33000 ppm.

Comparative Example 3

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by the externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of0.82 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 960 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing the homogenizer to obtain cuprous oxide dispersion liquid (copperoxide ink) of 1365 g.

The copper oxide particles were aggregated in the dispersion liquid,failing to produce ink. The content proportion of the cuprous oxide was20%. The hydrazine proportion was 3000 ppm.

Comparative Example 4

Copper acetate (II)-hydrate (manufactured by KANTO CHEMICAL CO., INC.)of) 806 g was dissolved in mixed solvent of distilled water(manufactured by KYOEI PHARMACEUTICAL CO., LTD.) of 7560 g and1,2-propylene glycol (manufactured by KANTO CHEMICAL CO., INC.) of 3494g, and the liquid temperature was set to −5° C. by the externaltemperature controller. Hydrazine-hydrate (manufactured by TokyoChemical Industry Co., Ltd.) of 235 g was added to the obtained solutionfor 20 minutes and stirred for 30 minutes. After that, the liquidtemperature was set to 25° C. by the external temperature controller andthe solution was stirred for 90 minutes. After the stirring, theobtained dispersion liquid was separated into supernatant andprecipitate by centrifugation. DisperBYK-145 (manufactured by BYK) of110 g, SURFLON 5611 (manufactured by SEIMI CHEMICAL) of 13.7 g, andethanol (manufactured by KANTO CHEMICAL CO., INC.) of 851 g were addedto the obtained precipitate of 390 g. The precipitate was dispersedusing the homogenizer to obtain cuprous oxide dispersion liquid (copperoxide ink) of 1365 g.

The copper oxide particles were aggregated in the dispersion liquid,failing to produce ink. The content proportion of the cuprous oxide was20%. The hydrazine proportion was 3000 ppm.

[Reverse Printing]

Using copper oxide ink, a patterned application film was formed on aboard by reverse printing. First, the application film of copper oxideink was formed at a uniform thickness on a surface of a blanket(transfer body). A material of the surface of the blanket is usuallymade of silicone rubber. Whether the copper oxide ink was properlyattached to this silicone rubber and the uniform application film wasformed were confirmed. Next, the surface of the blanket on which theapplication film of the copper oxide ink was formed was pressed againstand brought into contact with a letterpress plate, and a part of theapplication film of the copper oxide ink on the blanket surface wasattached to and transferred to surfaces of convex portions of theletterpress plate. Thus, a print pattern was formed on the applicationfilm of the copper oxide ink remaining on the surface of the blanket.Next, the blanket in this state was pressed against the surface of theprinted board to transfer the application film of the copper oxide inkremaining on the blanket, and thus the patterned application film wasformed. The evaluation criteria are as follows.

A: The reverse printing was able to be performed.

B: The print pattern was not formed in some parts.

C: The reverse printing was not able to be performed.

[Resistance Measurement]

A film having a thickness of 600 nm was manufactured on a PEN film usinga bar coater, was heated, fired, and reduced by a plasma firing deviceat 1.5 kw for 420 seconds to manufacture a copper film. A volumeresistivity of a conductive film was measured using a low resistivitymeter, Loresta-GP manufactured by Mitsubishi Chemical. Table 1 depictsperformance results of copper oxide inks and application films.

TABLE 1 Working example Comparative example 1 2 3 4 5 1 2 3 4 Reductantmass/ 0.015 0.0035 0.090 0.015 0.015 0.0 0.17 0.015 0.015 copper oxidemass Dispersing agent mass/ 0.20 0.20 0.20 0.0050 0.30 0.20 0.20 0.00300.40 copper oxide mass Evaluation Reverse A A A A A C C C C printingVolume 30 31 30 31 37 Measurement Measurement Measurement Measurementresistance impossible impossible impossible impossible (μΩcm)

In Working Example 1 to Working Example 5, the copper oxide inks werenot aggregated and low resistances were able to be maintained when thecopper films were manufactured on the PEN films. In the workingexamples, values of (reductant mass/copper oxide mass) were 0.0001 ormore to 0.10 or less, and values of (dispersing agent mass/copper oxidemass) were 0.0050 or more to 0.30 or less. It is considered that the useof hydrazine as the reductant promotes the reduction of the copper oxideand the copper film having the low resistance was manufactured.

In contrast to this, in Comparative Example 1 where the value of(reductant mass/copper oxide mass) was smaller than 0.001, it wasobserved that the copper oxide particles were partially aggregated inthe dispersion liquid. Additionally, a copper film was not able to beobtained by plasma firing and therefore the resistance was not able tobe measured. In Comparative Example 2 where the value of (reductantmass/copper oxide mass) was larger than 0.1, the copper oxide ink wasaggregated and therefore the reverse printing and the measurement of theresistance were not able to be performed. Moreover, both in ComparativeExample 3 where the value of (dispersing agent mass/copper oxide mass)was smaller than 0.005 and Comparative Example 4 where the value waslarger than 0.30, the copper oxide inks were aggregated and thereforethe reverse printing and the measurement of the resistance were not ableto be performed.

[Laser Firing]

The copper oxide ink of Working Example 1 was coated with a bar coateron a PET board so as to have a predetermined thickness (800 nm) and wasdried for ten minutes at room temperature to obtain a sample A in whichan application layer was formed on the PET.

The sample A was irradiated with laser light (wavelength: 445 nm,output: 1.1 W, a continuous wave (CW) oscillation) while a focusposition was moved at the maximum speed of 300 mm/minute using agalvanometer scanner to obtain a conductive film containing copper withdimensions of 25 mm×1 mm. The resistance was 20 μΩcm. A conductive filmwas able to be manufactured by laser firing as well.

Experimental Example 2 (Manufacturing Copper Oxide Particle DispersingElement)

A dispersing element containing copper oxide particles was manufacturedas follows.

Manufacturing Example 1

Copper acetate (II)-hydrate (manufactured by Wako Pure Chemical) of391.5 g was dissolved in mixed solvent of water of 3670 g and1,2-propylene glycol (manufactured by Wako Pure Chemical) of 1696 g, andhydrazine-hydrate (manufactured by Wako Pure Chemical) of 114 g wasadded and stirred. Afterwards, the solvent was separated intosupernatant and precipitate by centrifugation.

DISPERBYK-118 (manufactured by BYK) of 27.6 g and ethanol (manufacturedby Wako Pure Chemical) of 490 g were added to the obtained precipitateof 200 g as the dispersing agent and dispersed under a nitrogenatmosphere using the homogenizer.

Next, concentration with a UF membrane module and dilution with ethanolwere repeated, and further dilution with terpineol and concentrationwith a UF membrane were repeated to obtain a dispersing element S1 of225.4 g containing cuprous oxide having an average secondary particlediameter of 10 nm of 124 g. The average secondary particle diameter wasmeasured using FPAR-1000 manufactured by OTSUKA ELECTRONICS by cumulantmethod. The same applies to the following Manufacturing Examples 2 to 15and Comparative Manufacturing Examples 1 to 3.

Manufacturing Example 2

The copper acetate (II)-hydrate (manufactured by Wako Pure Chemical) of391.5 g was dissolved in water of 10880 g, and hydrazine-hydrate(manufactured by Wako Pure Chemical) of 114 g was added and stirred.Afterwards, the product was separated into supernatant and precipitateby centrifugation.

Hereinafter, a dispersing element S2 of 225.4 g containing cuprous oxideof 124 g having an average secondary particle diameter of 33 nm wasobtained by the combined amounts, the conditions, and the proceduressimilar to Manufacturing Example 1.

Manufacturing Example 3

Except for the use of DISPERBYK-118 (manufactured by BYK) of 6.9 g as adispersing agent, a dispersing element S3 of 204.7 g containing cuprousoxide of 124 g having an average secondary particle diameter of 10 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

Manufacturing Example 4

Except for the use of DISPERBYK-118 (manufactured by BYK) of 41.4 g as adispersing agent, a dispersing element S4 of 239.2 g containing cuprousoxide of 124 g having the average secondary particle diameter of 10 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

Manufacturing Example 5

Except for the use of DISPERBYK-118 (manufactured by BYK) of 6.9 g as adispersing agent, a dispersing element S5 of 204.7 g containing cuprousoxide of 124 g having an average secondary particle diameter of 33 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 2.

Manufacturing Example 6

Except for the use of DISPERBYK-118 (manufactured by BYK) of 41.4 g as adispersing agent, a dispersing element S6 of 239.2 g containing cuprousoxide of 124 g having an average secondary particle diameter of 33 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 2.

Manufacturing Example 7

Except for the use of DISPERBYK-118 (manufactured by BYK) of 4.1 g as adispersing agent, a dispersing element S7 of 201.9 g containing cuprousoxide of 124 g having an average secondary particle diameter of 10 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

Manufacturing Example 8

Except for the use of DISPERBYK-118 (manufactured by BYK) of 55.2 g as adispersing agent, a dispersing element S8 of 253.0 g containing cuprousoxide of 124 g having an average secondary particle diameter of 10 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

Manufacturing Example 9

Except for the use of DISPERBYK-118 (manufactured by BYK) of 4.1 g as adispersing agent, a dispersing element S9 of 201.9 g containing cuprousoxide of 124 g having an average secondary particle diameter of 33 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 2.

Manufacturing Example 10

Except for the use of DISPERBYK-118 (manufactured by BYK) of 82.9 g as adispersing agent, a dispersing element S10 of 280.6 g containing cuprousoxide of 124 g having an average secondary particle diameter of 33 nmwas obtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 2.

Manufacturing Example 11

Terpineol of 101.4 g was added to cuprous oxide of 124 g having a graindiameter of 150 nm and the product was dispersed under a nitrogenatmosphere using the homogenizer to obtain a dispersing element S11 of225.4 g.

Manufacturing Example 12

Except for the use of y-butyrolactone instead of the terpineol, adispersing element S12 of 225.4 g containing cuprous oxide of 124 g wasobtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

Manufacturing Example 13

Except for the use of cyclohexanol instead of the terpineol, adispersing element S13 of 225.4 g containing cuprous oxide of 124 g wasobtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1.

(Manufacturing Example 14)

Except for the use of ethylene glycol monoethyl ether acetate instead ofthe terpineol, a dispersing element S14 of 225.4 g containing cuprousoxide of 124 g was obtained by the combined amounts, the conditions, andthe procedures same as Manufacturing Example 1.

Manufacturing Example 15

Except for the use of tetralin instead of the terpineol, a dispersingelement S15 of 225.4 g containing cuprous oxide of 124 g was obtained bythe combined amounts, the conditions, and the procedures same asManufacturing Example 1.

Comparative Manufacturing Example 1

DISPERBYK-118 (manufactured by BYK) of 27.6 and terpineol of 73.8 g wereadded to cuprous oxide of 124 g having an average secondary particlediameter of 150 nm and the product was dispersed under a nitrogenatmosphere using the homogenizer to obtain a dispersing element H1 of225.4 g.

Comparative Manufacturing Example 2

Except for the use of toluene instead of the terpineol, a dispersingelement H2 of 225.4 g containing cuprous oxide of 124 g was obtained bythe combined amounts, the conditions, and the procedures same asManufacturing Example 1.

Comparative Manufacturing Example 3

Except for the use of butanol instead of the terpineol, a dispersingelement H3 of 225.4 g containing cuprous oxide of 124 g was obtained bythe combined amounts, the conditions, and the procedures same asManufacturing Example 1.

Working Examples 6 to 67

Any of the following copper particles A, B, C, D, and E was added to anyof the dispersing elements S1 to S15 of 40 g obtained in ManufacturingExamples 1 to 15 by the quantity depicted in Table 2. The product wasmixed under a nitrogen atmosphere by a rotary and revolutionary mixer toobtain dispersing elements of Working Examples 6 to 67. Table 2 depictsorganic compound mass ratios (BYK/Cu₂O) and copper particle mass ratios(Cu/Cu₂O) of these dispersing elements.

Copper particles A: needle-shaped copper powder (average particlediameter: 4.7 μm)

Copper particles B: dendritic-shaped copper powder (average particlediameter: 14.5 μm)

Copper particles C: scaly-shaped copper powder (1400YP manufactured byMITSUI MINING & SMELTING CO., LTD., average particle diameter: 4.9 μm)

Copper particles D: spherical-shaped copper powder (average particlediameter: 1 μm)

Copper particles E: spherical-shaped copper powder (average particlediameter: 5 μm)

Line patterns were printed on paper boards with the dispersing elementsof Working Examples 6 to 67 by screen-printing method. Then, using amicrowave plasma firing device, the dispersing elements were heated andfired at 1.5 kw for 420 seconds to form conductive films having widthsof 1 mm, lengths of 100 mm, and film thicknesses of 16 μm on the paperboards.

The dispersing elements of Working Examples 6 to 67 were evaluated fordispersion stability and continuous printability. Additionally, aninitial resistance, resistance stability, and a soldering performancewere measured on the conductive films obtained using the dispersingelements of Working Examples 6 to 67. Table 2 depicts the results.

The dispersion stability was evaluated as follows.

A . . . A period during which the screen-printing can be performed afterthe dispersing element is manufactured is 20 days or more

B . . . A period during which the screen-printing can be performed afterthe dispersing element is manufactured is five days or more to less than20 days

C . . . A period during which the screen-printing can be performed afterthe dispersing element is manufactured is less than five days

The screen-printing on the paper board was continuously performedmultiple times, and in the continuous printability, the number ofprintings that the screen-printing can be continuously performed wasfive times or more was evaluated as A and the number of printings thatthe screen-printing can be continuously performed was less than fivetimes was evaluated as B. Table 2 depicts the results.

The initial resistance is volume resistivity (unit: 10⁻⁵ Ω·cm) of theconductive film immediately after firing. The volume resistivity wasmeasured using Loresta-GP, the low resistivity meter manufactured byMitsubishi Chemical.

The resistance stability is expressed by a ratio of the volumeresistivity of the conductive film 100 days after the firing to thevolume resistivity of the conductive film immediately after the firing.

In a soldering test, a wire solder containing flux (tin: 60%, lead: 40%)was soldered to the paper board on which the conductive film was formedusing a soldering iron and the soldered part was visually observed. Thesoldering performance was evaluated as follows. In a case where thesurface of the conductive film was completely wet with the solder andcissing was not confirmed at all, it was evaluated as “A: no dewetting”and in a case where cissing was able to be confirmed even a little, itwas evaluated as “B: with dewetting.”

Working Examples 68 to 70

Line patterns were printed on paper boards with dispersing elements of6, 8, and 44 by screen-printing method. Then, using a light firingdevice manufactured by NovaCentrix, PulseForge 1300, light firing wasperformed at an energy density of 7 J/cm² and a pulse width of 8 msecsto form conductive films having widths of 1 mm, lengths of 100 mm, andfilm thicknesses of 16 μm on the paper boards.

The initial resistance and the resistance stability were measured on theconductive films thus obtained using the dispersing elements of WorkingExamples 68 to 70 and the soldering test was conducted. Table 2 depictsthe results.

A surface roughness measured on the surface of the conductive filmobtained using the dispersing element of Working Example 6 was 1340 nm.The surface roughness of the surface of the conductive film was measuredby the following method.

Measurement method: compliant with JIS B0601 2013 (ISO25178-2: 2012)

Measuring machine: laser microscope VK-X250 manufactured by KEYENCECORPORATION, lens magnification: 150 powers

The surface shape of the conductive film was measured at a center of anelectrode using the laser microscope. Arithmetic mean height wasobtained targeting an entire screen of an unevenness image obtained bythe laser microscope and was determined as the surface roughness.

Comparative Example 5

Ethanol of 98 g was added to the precipitate of 40 g obtained by thecombined amounts, the conditions, and the procedures same asManufacturing Example 1, and the precipitate was dispersed under anitrogen atmosphere using the homogenizer but was not dispersed.

Comparative Example 6

Ethanol of 98 g was added to the precipitate of 40 g obtained by thecombined amounts, the conditions, and the procedures same asManufacturing Example 2, and the precipitate was dispersed under anitrogen atmosphere using the homogenizer but was not dispersed.

Comparative Example 7

Terpineol of 98 g was added to a mixture of the precipitate obtained bythe combined amounts, the conditions, and the procedures same asManufacturing Example 1 and ethanol, and the precipitate was dispersedunder a nitrogen atmosphere using the homogenizer but was not dispersed.

Comparative Example 8

Terpineol of 98 g was added to a mixture of the precipitate obtained bythe combined amounts, the conditions, and the procedures same asManufacturing Example 2 and ethanol, and the precipitate was dispersedunder a nitrogen atmosphere using the homogenizer but was not dispersed.

Comparative Examples 9 to 11

Copper particles F: spherical-shaped copper powders (average particlediameter: 200 μm) of 88 g were added to the dispersing elements H1, S1,and S2 of 40 g obtained by Comparative Manufacturing Example 1 andManufacturing Examples 1 and 2, and the product was mixed under anitrogen atmosphere by the rotary and revolutionary mixer to obtaindispersing elements of Comparative Examples 9 to 11. Table 2 depictsorganic compound mass ratios (BYK/Cu₂O) and copper particle mass ratios(Cu/Cu₂O) of these dispersing elements.

Using the dispersing elements of Comparative Examples 9 to 11,conductive films were formed on paper boards with the conditionsidentical to those of Working Examples 6 to 67. The dispersing elementsof Comparative Examples 9 to 11 were evaluated for dispersion stabilityand continuous printability. Additionally, an initial resistance,resistance stability, and soldering performance were measured on theconductive films obtained using the dispersing elements of ComparativeExamples 9 to 11. Table 2 depicts the results.

Comparative Example 12

Diethylene glycol of 400 g was added to the precipitate of 200 gobtained by the combined amounts, the conditions, and the proceduressame as Manufacturing Example 1, and the precipitate was dispersed undera nitrogen atmosphere using the homogenizer to obtain a dispersingelement containing cuprous oxide.

Copper particles D: spherical-shaped copper powder (average particlediameter: 1 μm) of 88 g was added to this dispersing element of 40 g,and the dispersing element was mixed under a nitrogen atmosphere by therotary and revolutionary mixer to obtain a dispersing element ofComparative Example 12.

Although a line pattern of the dispersing element of Comparative Example12 was attempted to be printed on a paper board by screen-printingmethod, the aggregation of the copper particles proceeded rapidly andthe printing was not able to be performed.

Comparative Example 13

Terpineol of 18 g was added to the copper particles B of 88 g, and theproduct was mixed under a nitrogen atmosphere by the rotary andrevolutionary mixer to obtain a dispersing element of ComparativeExample 13. Since this dispersing element does not contain cuprous oxideparticles, the copper particle mass ratio (Cu/Cu₂O) is zero as depictedin Table 2.

Using the dispersing element of Comparative Example 13, a conductivefilm was formed on a paper board with the conditions identical to thoseof Working Examples 6 to 67. The initial resistance and the resistancestability were measured on the conductive film thus obtained using thedispersing element of Comparative Example 13. Table 2 depicts theresults.

Comparative Example 14

Copper particles were not added to the dispersing element S11 of 40 gobtained in Manufacturing Example 11, and the dispersing element S11 wasmixed under a nitrogen atmosphere by the rotary and revolutionary mixerto obtain a dispersing element of Comparative Example 14. The copperparticle mass ratios (Cu/Cu₂O) of these dispersing elements are zero asdepicted in Table 2.

Using the dispersing element of Comparative Example 14, a conductivefilm was formed on a paper board with the conditions identical to thoseof Working Examples 6 to 67. The initial resistance and resistorstability were measured on the conductive film thus obtained using thedispersing element of Comparative Example 14. Table 2 depicts theresults.

TABLE 2 Working example 6 7 8 9 10 11 12 13 14 15 Dispersing S1 40 g 40g 40 g 40 g element S2 40 g 40 g S3 40 g S4 40 g S5 40 g S6 40 g S7 S8S9 S10 S11 S12 S13 S14 S15 H1 H2 H3 Copper A (Needle 88 g 8

 g 88 g 88 g 22 g 154 g 8

 g 88 g particles shape) B (Dendritic) 44 g 44 g C (Scaly Shape) D(Spherical Shape, 1 μm) E (Spherical Shape, 5 μm) F (Spherical Shape,200 μm) BYK/Cu₂O 0 20 0.20 0.20 0.20 0.050 0.30 0.20 0.20 0.056 0.30Cu/C

O 4.0 4.0 2 0 2.0 4.0 4.0 1.0 7 0 4.0 4.0 Evaluation Dispersion A A A AA A A A A A stability Continuous A A A A A A A A A A printabilityInitial 2.7 2.97 5.8 6.4 1.4 5.4 4.1 5.4 1.5 5.9 resistance Resistance1.2 1.4 1.0 1.3 1.3 1.2 1.3 1.4 1.2 1.4 Stability Soldering A A A A A AA A A A performance Working example 16 17 18 19 20 21 22 23 24 25Dispersing S1 40 g 40 g element S2 40 g 40 g 40 g 40 g S3 40 g S4 40 gS5 40 g S6 40 g S7 S8 S9 S10 S11 S12 S13 S14 S15 H1 H2 H3 Copper A(Needle 22 g 154 g particles shape) B (Dendritic) 44 g 44 g 22 g 154 g44 g 44 g 22 g 154 g C (Scaly Shape) D (Spherical Shape, 1 μm) E(Spherical Shape, 5 μm) F (Spherical Shape, 200 μm) BYK/Cu₂O 0.20 0.200.050 0 30 0.20 0.20 0.050 0.30 0.20 0.26 Cu/C

O 1.0 7.0 4.0 4.0 4.0 7.0 4 0 4.0 1.0 7 0 Evaluation Dispersion A A A AA A A A A A stability Continuous A A A A A A A A A A printabilityInitial 4.5 5.9 2.9 12 8

11.8 3.19 12.76 9.57 1276 resistance Resistance 1.0 1.4 1.0 1.0 1 1 1.21 1.4 1.4 1.3 Stability Soldering A A A A A A A A A A performanceWorking example 26 27 28 29 30 31 32 33 34 35 Dispersing S1 40 g 40 gelement S2 40 g 40 g S3 S4 S5 S6 S7 40 g 40 g S8 40 g 40 g S9 40 g S1040 g S11 S12 S13 S14 S15 H1 H2 H3 Copper A (Needle

 g

8 g 11 g 220 g

8 g 8

 g 11 g 220 g particles shape) B (Dendritic) 44 g 44 g C (Scaly Shape) D(Spherical Shape, 1 μm) E (Spherical Shape, 5 μm) F (Spherical Shape,200 μm) BYK/Cu₂O 0.030 0.40 0.20 0.20 0.030 0.40 0.20 0.20 0.030 0.46Cu/C

O 4.0 4.0 0 50 10 4.0 4 0 0 50 10 4.0 4.0 Evaluation Dispersion B B B BB B B B B B stability Continuous A A A A A A A A A A printabilityInitial 4.1 8.1 5.4 8.1 4.5 8.9 5.9 8.9 8.7 17 resistance Resistance 1.31.2 1.3 1.4 1.3 1.2 1.4 13 1.0 1..0 Stability Soldering A A A A A A A AA A performance Working example 36 37 38 39 40 41 42 43 44 45 DispersingS1 40 g 40 g 40 g 40 g 40 g element S2 40 g 40 g S3 40 g S4 S5 S6 S7 S8S9 40 g S10 S11 S12 S13 S14 S15 H1 H2 H3 Copper A (Needle particlesshape) B (Dendritic) 11 g 220 g 44 g 44 g 11 g 220 g C (Scaly 88 g

8 g Shape) D (Spherical 88 g Shape, 1 μm) E (Spherical 88 g Shape, 5 μm)F (Spherical Shape, 200 μm) BYK/Cu₂O 0.20 0.20 0.036 0.40 0.20 0.20 0.200.20 0.20 0.050 Cu/C

O 0.50 10 4.0 4.0 0.50 10 4.0

0 4.0 4.0 Evaluation Dispersion B B B B B B A A A A stability ContinuousA A A A A A A A A A printability Initial 12 17 9.

19 13 19 7.0 9.2 2.5 1.3 resistance Resistance 1.1 1.2 11 1.1 1.0 1.32.8 2.8 1.0 1.0 Stability Soldering A A A A A A A A A A performanceWorking example 46 47 48 49 50 51 52 53 54 55 Dispersing S1 40 g 40 g 40g 40 g element S2 S3 S4 S5 S6 S7 40 g S8 40 g S9 S10 S11 40 g 40 g 40 gS12 S13 S14 S15 H1 H2 H3 Copper A (Needle 88 g particles shape) B(Dendritic) 44 g C (Scaly 88 g 22 g 154 g 88 g 88 g 11 g 320 g

8 g Shape) D (Spherical Shape, 1 μm) E (Spherical Shape, 5 μm) F(Spherical Shape, 200 μm) BYK/Cu₂O 0.30 020 0.20 0.030 0.40 0.20 0.200.0 0.0 0.0 Cu/C

O 4.0 1.0 7.0 4.0 4.0 0.50 10 4.0 2.0 4.0 Evaluation Dispersion A A A BB B B B B B stability Continuous A A A A A A A A A A printabilityInitial 5.0 3.8 50 3.8 7.5 5.0 7.5 3.2 6.5 4.3 resistance Resistance 1.01.1 1.2 1.0 1.0 1.1 1.2 1.3 1.3 1.2 Stability Soldering A A A A A A A AA A performance Working example 56 57 58 59 60 61 62 63 64 65 DispersingS1 element S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 40 g 40 g 40 g S13 40 g40 g 40 g S14 40 g 40 g 40 g S15 40 g H1 H2 H3 Copper A (Needle

8 g 88 g particles shape) B (Dendritic) 88 g 88 g 44 g C (Scaly 44 g 44g 88 g 88 g Shape) D (Spherical 38 g Shape, 1 μm) E (Spherical Shape, 5μm) F (Spherical Shape, 200 μm) BYK/Cu₂O 0.20 0.20 0 20 0 20 0.20 0.200.20 0.20 0.20 0.20 Cu/C

O 4.0

.0 4.0 4.0 2.0 4.0 2.0 2.0 4.0 4.0 Evaluation Dispersion A A A A A A A AA A stability Continuous A A A A A A A A A A printability Initial 3.06.1 2.9 3.5 7.1 2.7 2.7 7.1 2.6 3.3 resistance Resistance 1.1 1.3 1.31.1 1.2 1.2 1.1 1.2 1.2 1.1 Stability Soldering A A A A A A A A A Aperformance Working example 66 67 68 69 70 Dispersing S1 40 g 40 g 40 gelement S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 40 g 40 g H1 H2H3 Copper A (Needle 88 g particles shape) B (Dendritic) 44 g 44 g C(Scaly 88 g 88 g Shape) D (Spherical Shape, 1 μm) E (Spherical Shape, 5μm) F (Spherical Shape, 200 μm) BYK/Cu₂O 0.20 0.20 0.20 0 20 0.20 Cu/C

O 0.20 4.0 40 2.0 4.0 Evaluation Dispersion A A A A A stabilityContinuous A A A A A printability Initial 7.2 3.0 1 9 1.8 1.6 resistanceResistance 1.1 1.2 1 1 1 1.0 Stability Soldering A A A A A performanceComparative Example 9 10 11 13 14 15 16 Dispersing S1 40 g element S2 40g S3 S4 S5 S6 S7 S8 S9 S10 S11 40 g S12 S13 S14 S15 H1 40 g H2 40 g H340 g Copper A (Needle 88 g 88 g particles shape) B (Dendritic) 88 g C(Scaly Shape) D (Spherical Shape, 1 μm) E (Spherical Shape, 5 μm) F(Spherical 88 g 88 g 88 g Shape, 200 μm) BYK/Cu₂O 0.20 0.20 0.20 0.0 0.00.20 0.20 Cu/Cu₃O 4.0 4.0 4.0 0.0 0.0 4.0 4.0 Evaluation Dispersion C BB A A A A stability Continuous A A A A A B B printability Initial 9.58.0 10 26 23 3.3 3.5 resistance Resistance 3.0 3.2 3.2 1.9 2.4 1.2 1.3Stability Soldering A A A A A A A performance

indicates data missing or illegible when filed

As apparent from Table 2, when the copper particles A: needle-shapedcopper powder (average particle diameter: 4.7 μm), the copper particlesB: the dendritic-shaped copper powder (average particle diameter: 14.5μm), the copper particles C: the scaly-shaped copper powder (averageparticle diameter: 4.9 μm), the copper particles D: spherical-shapedcopper powder (average particle diameter: 1 μm), and the copperparticles E: spherical-shaped copper powder (average particle diameter:5 μm) were added to the dispersing elements S1 to S15 containing thecuprous oxide particles having the average secondary particle diametersof 10 nm or 33 nm, and DISPERBYK-118, which is an example of the organiccompound having the phosphate group, was used, it has been confirmedthat the obtained dispersing elements of Working Examples 6 to 67 wereexcellent in dispersion stability and also excellent in continuousprintability. Additionally, it has been confirmed that the conductivefilms of Working Examples 6 to 67, which were obtained by using thedispersing elements of Working Examples 6 to 67, printing the linepatterns by screen-printing method, and performing the firing process,had the low initial resistances and were excellent in resistancestability and further were excellent in soldering performance.

From these results, it has been confirmed that the dispersing elementcontaining the copper oxide particles having the average secondaryparticle diameters of 1 nm or more to 50 nm or less, the copperparticles having the particle diameters of 0.1 μm or more to 100 μm orless, and the organic compound having the phosphate group is excellentin dispersion stability and the screen-printing is possible even after along period passes after manufacturing the dispersing element.Additionally, it has been found that the conductive film obtained usingthe dispersing element has the low initial resistance and is excellentin resistance stability. Further, the conductive film is found to beexcellent in soldering performance. The mass ratio of the organiccompound having the phosphate group to the mass of the copper oxide isfound to be preferred from 0.0050 or more to 0.40 or less and morepreferred from 0.0050 or more to 0.30 or less.

From these results, it has confirmed that in Working Examples 6 to 67 inwhich the copper particles A: needle-shaped copper powder, the copperparticles B: the dendritic-shaped copper powder, and the copperparticles C: scaly-shaped copper powder were added to the dispersingelements S1 to S15 containing the cuprous oxide particles, theconductive films obtained by using the dispersing elements, printing theline patterns by screen-printing method, and performing the firingprocess had the low initial resistances and were excellent in resistancestability. Additionally, the soldering performance was also excellent.The same applies to Working Examples 68 to 70.

As described above, it has been found that the conductive films usingthe dispersing elements of the working examples are excellent insoldering performance. Accordingly, it has been confirmed that a failureof the solder bonding portion bonded to the conductive film and thebonded portion of the electronic component can be prevented and theboards with the electronic components can be manufactured at a highyield.

Furthermore, as seen from the evaluation on the initial resistance andthe resistance stability of the conductive films, it has been confirmedthat the board with the electronic component having the excellentperformance can be obtained.

It has been confirmed that, although Working Examples 53 to 55 using thedispersing element S11 do not use the dispersing agent (DISPERBYK-118),the screen-printing is possible, and further the initial resistance islow and the resistance stability is excellent. The excellent solderingperformance has been confirmed. Thus, it has been confirmed that the useof the dispersing agent does not affect the effects of the dispersingelement of the embodiments.

Meanwhile, with the dispersing elements of Comparative Example 5 toComparative Example 8 that do not use DISPERBYK-118, which is oneexample of the organic compound having the phosphate group, thescreen-printing was not able to be performed.

Moreover, the dispersing element of Comparative Example 9 containing thecuprous oxide particles having the average secondary particle diameterof 150 nm and the copper particles F: spherical-shaped copper powderhaving the particle diameter of 200 μm was evaluated as C for dispersionstability. It has been confirmed that the conductive film obtained usingthe dispersing element had the low initial resistance and was excellentin soldering performance but was poor in resistance stability.

The dispersing elements of Comparative Examples 10 and 11 produced byadding the copper particles F: spherical-shaped copper powder having theparticle diameter of 200 μm to the dispersion liquids S1 and S2 wereevaluated as B for dispersion stability. However, it has been confirmedthat the conductive films obtained using these dispersing elements hadthe low initial resistance and were excellent in soldering performancebut were poor in resistance stability.

The screen-printing was not able to be performed in Comparative Example12. It has been confirmed that like Comparative Examples 13 and 14, inthe case where any one of the cuprous oxide particles or the copperparticles is contained, although the screen-printing is possible, theinitial resistance is high and the resistance stability is low.

Comparative Examples 15 and 16

The copper particles A of 88 g were added to the dispersing elements H2and H3 of 40 g obtained in Comparative Manufacturing Examples 2 and 3,and the products were mixed with the rotary and revolutionary mixerunder a nitrogen atmosphere to obtain the dispersing elements ofComparative Examples 15 and 16. Table 2 depicts the copper particle massratios (Cu/Cu₂O) of these dispersing elements.

Conductive films were formed on paper boards with the conditionsidentical to Working Examples 6 to 67 using the dispersing elements ofComparative Examples 15 and 16. The initial resistances were measured onthe conductive films thus obtained using the dispersing elements ofComparative Examples 15 and 16. The continuous printability wasevaluated on the dispersing elements of Comparative Examples 15 and 16.Table 2 depicts these results.

As apparent from Table 2, it has been confirmed that the conductivefilms obtained by printing the line patterns by screen-printing methodusing the dispersing elements of Working Example 53 to 67 produced byadding the copper particles A: needle-shaped copper powder, the copperparticles B: the dendritic-shaped copper powder, and the copperparticles C: scaly-shaped copper powder to the dispersing elements S11to S15 containing the cuprous oxide particles using terpineol,y-butyrolactone, cyclohexanol, ethylene glycol monoethyl ether acetate,and tetralin as the dispersion mediums and performing the firing processhad the low initial resistances. The dispersing elements were evaluatedas A for continuous printability.

As depicted in Table 2, Comparative Examples 15 and 16 using toluene andbutanol as the dispersion mediums had the low initial resistances butevaluated as B for continuous printability. From these results, it hasbeen confirmed that terpineol, y-butyrolactone, cyclohexanol, ethyleneglycol monoethyl ether acetate, and tetralin contribute to theimprovement in continuous printability.

Accordingly, like Working Examples 53 to 67 disclosed in Table 2, it hasbeen found that the use of the dispersing element containing the cuprousoxide particles, the needle-shaped, the dendritic-shaped, or thescaly-shaped copper particles, containing any of terpineol,y-butyrolactone, cyclohexanol, ethylene glycol monoethyl ether acetate,and tetralin as the dispersion medium, and containing the organiccompound having the phosphate group allows obtaining the conductive filmhaving the low initial resistance and the excellent continuousprintability by screen-printing method.

Comparative Example 17

A line pattern was printed on a paper board using a copper paste CP-1Pfor screen-printing manufactured by NOF CORPORATION., which did notcontain cuprous oxide particles and did not contain an organic compoundhaving a phosphate group by screen-printing method, and then plasmafiring was performed with the conditions similar to Working Examples 6to 67 to form a conductive film on the paper board.

While a soldering test was conducted on the obtained conductive film ofComparative Example 17, dewetting was present and the evaluation was B.The surface roughness of the conductive film was measured, and thesurface roughness was 858 nm.

As apparent from Table 2, it has been confirmed that in the case wherethe copper particles A: needle-shaped copper powder, the copperparticles B: dendritic-shaped copper powder, and the copper particles C:scaly-shaped copper powder were added to the dispersing elements S1, 3,4, 7, and 8 containing the cuprous oxide particles, the conductive filmsobtained by printing the line patterns by screen-printing method usingthe dispersing elements and performing the firing process exhibited thelow initial resistance, the high resistance stability, and the excellentsoldering performance.

Although the screen-printing was able to be performed in ComparativeExample 17, the soldering performance was evaluated as B and thesoldering performance was inferior. This result suggests that, althoughthe use of the copper paste allowed the screen-printing, the organiccomponent generating the dewetting remained in the conductive film afterthe plasma firing; therefore, the soldering performance was poor.

claim 1 is based on Experimental Example 1. Claims 2 and 3 are based onExperimental Example 2.

Note that the present invention is not limited to the above-describedembodiments and respective working examples. Based on knowledge of aperson skilled in the art, for example, a design of the embodiments andthe respective working examples may be changed. Additionally, theembodiments and the respective working examples may be in any givencombination, and the aspect adding such a change and the like is withinthe scope of the present invention.

This application is a divisional application of U.S. application Ser.No. 16/491,115, filed Sep. 4, 2019, which is a § 371 application ofPCT/JP2018/010287, filed Mar. 15, 2018, which application is based onJapanese Patent Application No. 2017-51568, Japanese Patent ApplicationNo. 2017-51569, Japanese Patent Application No. 2017-51570, JapanesePatent Application No. 2017-51571, and Japanese Patent Application No.2017-51572 filed on Mar. 16, 2017, and Japanese Patent Application No.2017-145188 filed on Jul. 27, 2017, and Japanese Patent Application No.2018-23239 and Japanese Patent Application No. 2018-23242 filed on Feb.13, 2018. The entire contents of which are incorporated herein byreference.

1-13. (canceled)
 14. A method for manufacturing a structure with aconductive pattern comprising: a step of applying a dispersing elementover a board to form an application film; and a step of irradiating theapplication film with laser light to form a conductive pattern on theboard, wherein the dispersing element includes a copper oxide, adispersing agent, and a reductant, wherein content of the reductant isin a range of a following formula (1), and wherein content of thedispersing agent is in a range of a following formula (2):0.0001≤(reductant mass/copper oxide mass)≤0.10  (1)0.0050≤(dispersing agent mass/copper oxide mass)≤0.30  (2). 15-20.(canceled)
 21. The method for manufacturing the structure with theconductive pattern according to claim 14, wherein after the applicationfilm is formed on a transfer body, the application film is transferredfrom the transfer body to the board to form the application film on theboard.
 22. (canceled)
 23. The method for manufacturing the structurewith the conductive pattern according to claim 14, wherein theconductive pattern is an antenna.
 24. The method for manufacturing thestructure with the conductive pattern according to claim 23, wherein theconductive pattern has a mesh shape.
 25. The method for manufacturingthe structure with the conductive pattern according to claim 14, furthercomprising a step of forming a solder layer on a part of a surface ofthe conductive pattern.
 26. The method for manufacturing the structurewith the conductive pattern according to claim 25, wherein on theconductive pattern, an electronic component is soldered via the solderlayer by a reflow method.
 27. A structure with a conductive patterncomprising: a board; a cuprous-oxide-containing layer formed on asurface of the board; and a conductive layer formed on a surface of thecuprous-oxide-containing layer, wherein the conductive layer is a wiringhaving a wire width of 1 μm or more to 1000 μm or less, and the wiringcontains a reduced copper.
 28. (canceled)
 29. A structure with aconductive pattern comprising: a board; and a conductive pattern formedon a surface of the board, wherein the conductive pattern is a wiringhaving a wire width of 1 μm or more to 1000 μm or less, and the wiringcontains a reduced copper, a phosphorus, and a void. 30-31. (canceled)32. The structure with the conductive pattern according to claim 27,wherein the conductive layer or the conductive pattern has a surfacehaving a surface roughness of 500 nm or more to 4000 nm or less.
 33. Thestructure with the conductive pattern according tony claim 27, whereinthe wiring is usable as an antenna.
 34. The structure with theconductive pattern according to claim 27, wherein the conductive layeror the conductive pattern has a surface on which a solder layer ispartially formed.
 35. A structure with a conductive pattern comprising:a board; and a conductive pattern formed on the board surface, whereinthe conductive pattern is a wiring having a wire width of 1 μm or moreto 1000 μm or less, the wiring contains a reduced copper, a copperoxide, and a phosphorus, and a resin is disposed so as to cover thewiring.
 36. The method for manufacturing the structure with theconductive pattern according to claim 14, wherein the dispersing agentis a phosphorus-containing organic matter.